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USOO5557014A
United States Patent (19) 11) Patent Number: 5,557,014
Grate et al. (45) Date of Patent: Sep. 17, 1996

54 CATALYTIC SYSTEM FOR OLEFIN Polotebnova, N.A., et al., Zh. Neorg. Khim. (1973) 18:413.
OXDATION TO CARBONYL PRODUCTS The English translation edition, "Properties of Vanadomo
lybdophosphoric Acids with Varying Concentrations of
75 Inventors: John H. Grate; David R. Hamm, both Molybdenum and Vanadium', Russian Journal of Inorganic
of Mountain View; Kenneth A. Chemistry (1973) 18(2):216-219, is provided.
Kingman, San Mateo, all of Calif.; Zangen, M., "Solvent Extraction From Molten Salts. V.
Robert J. Saxton, West Chester, Pa.; Zinc(II) Chloride, Bromide, and Iodide', Inorg. Chem.,
Shannan J. Downey, Fremont, Calif. (1968) 7(1):133-138. Page 137 is provided.
Matveev, K. I., Kinetika i Katal. (1977) vol. 18, No. 4, pp.
73) Assignee: Catalytica, Inc., Mountain View, Calif. 862-877. The English translation edition, “Development of
New Homogeneous Catalysts for the Oxidation of Ethylene
21 Appl. No.: 558,202 to Acetaldehyde', pp. 716–727, is provided.
Cihova, M., et al., "Catalytic Oxidation of Octene-1 in the
22 Filed: Nov. 16, 1995 Presence of Palladium(II) Salts and Heteropolyacids', Reac
tion Kinetics and Catalysis Letters, (1981) 16:383-386.
Related U.S. Application Data Cihova, M., et al., “Oxidacia 1-okténu na 2-octanón v
prietoônom reaktore', Ropa Uhlie (1986) 28:297-302. An
63 Continuation of Ser. No. 461,223, Jun. 5, 1995, abandoned, English language abstract (Chem. Abstr. 107(1):6740r) is
which is a continuation of Ser. No. 689,050, Sep. 4, 1992, attached.
abandoned, which is a continuation-in-part of Ser. No. El Ali, Bassam, et al., "Oxydation catalytique de l'octéne-1
489,806, Mar. 5, 1990, abandoned.
en présence de complexes de rhodium(III) ou de palla
(5ll int. Cl. ...................................... C07C 45/35 dium(II) associés à des acides phosphomolybdovanadiques
(52) 568/401; 568/360; 568/478 et audioxygène', J. Organomet. Chem. (1987)327:C9-C14.
58) Field of Search ..................................... 568/360, 401, The publication includes an English language abstract.
568,478 Kuznetsova, L. I., et al., "Catalytic Oxidation of Vanadyl
Salts by Oxygen in the Presence of Sodium Molybdate',
(56) References Cited Reaction Kinetics and Catalysis Letters (1975)
3(3):305-310.
U.S. PATENT DOCUMENTS Kuznetsova, L.I., et al., Koordinatsionnaya Khimiya (1977)
3,119,875 1/1964 Steinmetz ................................ 260,604 vol. 3., No. 1, pp. 51-58. The English translation edition,
3,122,586 2/1964 Berndt...... ... 260,586 "State of Phosphomolybdovanadium Heteropoly Blue
3,154,586 10/1964 Bander . ... 260,596 Oxides in Aqueous Solution”, pp.39-44, is provided.
3,485,877 12/1969 Hargis . ... 260/604 Berdnikov, V.M., et al., Koordinatsionnaya Khimiya (1979)
4,146,574 3/1979 Onada .. ... 42.3/299 vol. 5, No. 1, pp. 78-85. The English translation edition
4,404,397 9/1983 Daniel .. ... 562.546 Kinetics and Mechanism of the Oxidation of Reduced
4,434,082 2/1984 Murtha . ... 502f 64 Molybdovanadophosphoric Heteropolyacids with Oxygen
4,448,892 5/1984 Kukes ...... ... 502A64
4,507,506 3/1985 Shioyama. ... 568,401 Hexavanadic Heteropoly Blues", pp. 60-66, is provided.
4,507,507 3/1985 Murtha ..... ... 568/401 (List continued on next page.)
4,532,362 7/1985 Kukes ...... ... 568,401
4.550,212 10/1985 Shioyama. ... 568,401 Primary Examiner-James H. Reamer
4,720,474 1/1988 Vasilevskis ... ... 502f165
4723,041 2/1988 Vasilewskis ... ... 568/401 Attorney, Agent, or Firm-John H. Grate
4,762,817 8/1988 Logsdon ... ... 502/.329 57 ABSTRACT
5,004,845 4/1991 Bradley ................................... 568/885
FOREIGN PATENT DOCUMENTS The present invention provides aqueous catalyst solutions
useful for oxidation of olefins to carbonyl products, com
828603 10/1975 Belgium. prising a palladium catalyst and a polyoxoacid or poly
0031729 7/1981 European Pat. Off.. oxoanion oxidant comprising vanadium. It also provides
123085 11/1976 Germany. processes for oxidation of olefins to carbonyl products,
61-43131 3/1986 Japan. comprising contacting olefin with the aqueous catalyst solu
1508331 4/1978 United Kingdom. tions of the present invention. It also provides processes for
OTHER PUBLICATIONS oxidation of olefins to carbonyl products by dioxygen,
comprising contacting olefin with the aqueous catalyst solu
Smidt, J., et al., “The Oxidation of Olefins with Palladium tions of the present invention, and further comprising con
Chloride Catalysts', Angew. Chem. Internat. Edit, vol. 1, pp. tacting dioxygen with the aqueous catalyst solutions. In
80-88. certain aqueous catalyst solutions and related processes of
Miller, S.A., editor, Ethylene and Its Industrial Derivatives the present invention, the solution has a hydrogen ion
(published by Ernest Benn Ltd, London, 1969), Chapter 8, concentration greater than 0.10 mole per liter when essen
pp. 639-689. tially all of the oxidant is in its oxidized state. In other
Matveev, K. I., et al., Kinetika i Kataliz (1977) vol. 18, No.
aqueous catalyst solution and related processes of the
2, pp. 380–386. The English translation edition, "Kinetics of present invention, the solution is essentially free of sulfuric
acid and sulfate ions.
Oxidation of Ethylene to Acetaldehyde by Phosphomolyb
dicvanadic Heteropolyacids in the Presence of a Pd(II) Aquo
Complex', pp. 320-326, is provided. 19 Claims, 3 Drawing Sheets
 5,557,014
Page 2

OTHER PUBLICATIONS Davison, S. F., Ph.D. Dissertation, "Palladium and Het

eropolyacid Catalyzed Oxidation of Butene to Butanone',
Kozhevnikov, I. V., Izvestiya Akademi Nauk SSSR, Seriya University of Sheffield, 1981. The Summary, Table of Con
Khimicheskaya (1981) No. 11., pp. 2428-2435. The English tents, pages 63 and 77, are provided.
translation edition, "Mechanism of the Oxidation of Pope, Michael Thor, Inorganic Chemistry Concepts 8: Het
12-Molybovanadophosphate Blue by Oxygen in Aqeuous eropoly and Isopoly Oxometalates, published by Spring
Solution', pp. 2001-2007, is provided. er-Verlag, NY. A copy of the Table of Contents is provided.
Burov, Y. V., et al., Izvestiya Akademi Nauk SSSR, Seriya Koscielski, T., et al., "Catalytic Hydrogenation on Raney
Khimicheskaya (1980) No. 7, pp. 1469–73. The English
translation edition, "Steady-Flow Investigation of the Kinet Nickel Catalyst Modified by Chromium Hydroxide Depo
ics of the Reaction Between VO” and Phosphorus-Molyb sition”, Applied Catalysis (1989) 49:91-99.
denum-Vanadium Heteropoly Anions', pp. 1017-1021, is Sixth World Petroleum Congress Proceedings, Section IV,
provided. Paper 40, pp. 461–466, Frankfurt, 19–26 Jun. 1963.
Kuznetsova, L. I., et al., “Mechanism of Oxidation of "New Process for Acetone and MEK: A Special Report: 6th
Molybdovanadophosphoric Heteropoly Blues by Molecular World Petroleum Congress', in Hydrocarbon Processing &
Oxygen. Trivanadium Heteropoly Blue', Reaction Kinetics Petroleum Refiner (1963) vol. 42, pp. 149-152.
and Catalysis Letters (1981) 17:401–406. "Wacker Process Can Make Acetone, MEK', in Chemical
Davison, S. F., et al., "Phosphomolybdic Acid as a Reoxi and Engineering News, 8 Jul. 1963, pp. 50–51.
dant in the Palladium(II)-catalysed Oxidation of But-1-ene Bonnier, J-M., et al., “Raney Nickel as a Selective Catalyst
to Butan-2-one', J. Chem. Soc. Dalton Trans. (1984) pp. for Aldehyde Reduction in the Presense of Ketones',
223-1228. Applied Catalysis (1987) 30:181-184.
U.S. Patent Sep. 17, 1996 Sheet 1 of 3 5,557,014

FIGURE

seo(tluhmyin)/selcotPmM0.10withdrotererdto(hcyItlie)one
O.O

-log(H+), (H+ in mole/liter)

free of Sulfate O Contain Sulfate
U.S. Patent Sep. 17, 1996 Sheet 2 of 3 5,557,014

FIGURE 2

25

2O

O.OO O.O 0.2O O.30

palladium concentration, millimole/liter
U.S. Patent Sep. 17, 1996 Sheet 3 of 3 5,557,014

FIGURE 3

16

14
2S
S
ud
12
N
gs
25 10
Cd
o Co
us is2
ES 8
C
3, 5
3.39 6
C2
O
S 4
E

O 2 3
impeller stirring rate, RPM/1000
 5,557,014
1 2
CATALYTIC SYSTEM FOR OLEFIN disclosed in U.S. Pat. Nos. 3,122,586, 3,119,875, and 3,154,
OX DATION TO CARBONYL PRODUCTS 586, each incorporated by reference entirely.
In the Wacker process chemistry, ethylene is oxidized by
CROSS-REFERENCES TO RELATED cupric chloride in aqueous solution, catalyzed by palladium:
APPLICATIONS 2
This application is a for a continuation of prior patent C2H4+ 2CullCl2 + H2O - - - Ge. (2)
CHCHO + 2CuC + 2H
application Ser. No. 08/461,223, now abandoned, filed Jun. In a typical manufacturing operation, copper is present in
5, 1995 entitled CATALYTIC SYSTEM FOR OLEFIN
OXIDATION TO CARBONYL PRODUCTS, which is a for O
the aqueous solution at concentrations of about 1 mole per
a continuation of prior patent application Ser. No. 07/689, liter, total chloride is present at concentrations of about 2
moles per liter, and the palladium catalyst is present at
050, now abandoned, filed Sep. 4, 1992 entitled CATA concentrations of about 0.01 moles per liter. Under these
LYTIC SYSTEM FOR OLEFIN OXIDATION TO CAR conditions, palladium(II) exists predominantly as the tetra
BONYL PRODUCTS, which is a continuation-in-part of chloropalladate ion, PdCl4. Cuprous chloride resulting
U.S. patent application Ser. No. 489,806 filed Mar. 5, 1990, 15 from the oxidation of ethylene is solubilized in the aqueous
now abandoned, which is incorporated by reference entirely. solution by the co-produced hydrochloric acid, as the dichlo
Related U.S. patent applications Ser. Nos. 07/689,048 filed rocuprate ion, Cu'Cl. In a subsequent Wacker chemistry
Sep. 4, 1992, now abandoned, and 07/675,932, filed Sep. 2, step, this reduced copper is reoxidized by reaction with
1992 now abandoned, 07/934,643 filed Sep. 4, 1992 co-filed dioxygen:
with Ser. No. 07/689,050, now abandoned, are each incor 20
porated by reference entirely.
FIELD OF THE INVENTION
(Reactions (2) and (3) combined give overall reaction
This invention relates generally to oxidation of olefins to 25 (1)).
carbonyl compounds. More specifically, it relates to oxida Two acetaldehyde manufacturing processes, a two-stage
tion of olefins to carbonyl compounds by polyoxoanion process and a one-stage process, have been developed and
oxidants in aqueous solution, catalyzed by palladium. In operated using the Wacker system chemistry. In the two
another aspect, it relates to reoxidation of reduced poly stage process, ethylene oxidation by cupric chloride, reac
oxoanions in aqueous solution by reaction with dioxygen. It 30 tion (2), and reoxidation of cuprous chloride by air, reaction
further relates to an overall process for the oxidation of (3), are conducted separately, with intermediate removal of
olefins to carbonyl compounds by dioxygen catalyzed by the acetaldehyde product from the aqueous solution. The
palladium and polyoxoanions in aqueous solution. reoxidized aqueous solution is recycled to the ethylene
oxidation stage. The reactions are conducted attemperatures
BACKGROUND OF THE INVENTION 35 of about 100 to 130° C. in reactors which, by providing
The catalyst solutions and the processes of the present very efficient gas-liquid mixing, result in high rates of
invention are useful for the production of aldehydes, diffusion (mass transfer) of the reacting gas into the aqueous
ketones, and carboxylic acids, which are chemicals of com solution. Under these conditions, about 0.24 moles ethylene
merce and/or feedstocks for the production of chemicals and per liter of solution can be reacted within about 1 minute in
materials of commerce. For example, acetone, methyl ethyl 40 the ethylene reactor, corresponding to an average ethylene
ketone and methyl isobutyl ketone are used as solvents. reaction rate of about 4 (millimoles/liter)/second. With a
Acetaldehyde is used in the production of acetic acid, typical palladium concentration of about 0.01 moles per
polyols, and pyridines. Acetic acid is used in the production liter, this corresponds to a palladium turnover frequency (a
of vinyl acetate, cellulose acetate, and various alkyl acetate measure of catalyst activity) of about 0.4 (moles CH/mole
esters which are used as solvents. Acetone is used in the 45 Pd)/second. In the air reactor, about 0.12 moles dioxygen per
production of methylmethacrylate for polymethylmethacry liter of solution can be reacted within about 1 minute,
late. Cyclohexanone is used in the production of caprolac corresponding to an average dioxygen reaction rate of about
tan for nylon-6 and adipic acid for nylon-6,6. Other cyclic 2 (millimoles/liter)/second.
ketones can be used for the production of other nylon-type In the one-stage process, ethylene and dioxygen are
polymers. 50 simultaneously reacted with the aqueous solution, from
Acetaldehyde is industrially produced by the Wacker which acetaldehyde is continuously removed.
Palladium catalyzes the oxidation of ethylene by cupric
oxidation of ethylene by dioxygen, which uses an aqueous chloride (reaction (2)) by oxidizing ethylene (reaction (4))
catalyst system of palladium chloride, copper chloride, and and then reducing cupric chloride (reaction (5)):
hydrochloric acid to accomplish the following net conver 55
SO
CH+PdCl4-HO-CHCHO--Pd+2 H+4 Cl (4)
CH+%O-CHCHO (1) Pd-4 C-2 Cu'Cl-)PdCl42 CuCl (5)
Reviews of the Wacker process chemistry and manufac 60 Functionally, the copper chlorides mediate the indirect
turing processes for the direct oxidation of ethylene to reoxidation of the reduced palladium(0) by dioxygen via
acetaldehyde can be found in "The Oxidation of Olefins with reaction (5) plus reaction (3). Direct oxidation of palla
Palladium Chloride Catalysts', Angew. Chem, internat. dium(0) by dioxygen is thermodynamically possible but is
Edit., Vol. 1 (1962), pp. 80–88, and in Chapter 8 of Ethylene far too slow for practical application.
and its Industrial Derivatives, S. A. Miller ed., Ernest Benn 65 The overall rate of oxidation of ethylene by the Wacker
Ltd., London, 1969, each of which is incorporated by system is limited by the rate of oxidation of ethylene by the
reference entirely. Aspects of Wacker technology are also tetrachloropalladate (reaction (4)). The reaction rate is
 5,557,014
3 4
inversely dependent on both the hydrogen ion concentration hydrochloric acid to ethylene, giving ethylchloride, and to
and the square of the chloride ion concentration, having the olefinic by-products. Others result from palladium centered
following concentration dependencies: oxychlorination, for example, 2-chloroethanol from ethyl
ene. The predominant origin of chlorinated organic by
products is oxychlorination by cupric chloride; most arise
CH, reaction rateo-PdClCH/(HCl (6) from copper centered oxychlorination of acetaldehyde, giv
Two chloride ions must be dissociated from tetrachloro
ing chloroacetaldehydes, and further reactions of the chlo
roacetaldehydes. Accordingly, we determined that most of
palladate before palladium(II) productively binds both the the objectionable chlorinated organic by-product yield
substrates of reaction (4), ethylene and water. Said another 10 results not simply from the presence of chloride, but from
way, chloride competes with the two substrates for the third the combination of chloride and copper.
and fourth coordination sites on palladium(II). This occurs Aqueous palladium(II) salts also oxidize higher olefins to
by the following equilibria: carbonyl compounds according to equation (11), where R,
R', and R" are hydrocarbyl substituent groups and/or hydro
gen (R=R'-R"=H for ethylene):
PdCl4-CH, PdCl(CH)+Cl (7) 5
RR'C=CHR" + Pd 4-HO-Ge (11)
PdCl(CH) +HOePdCl2(CH)(HO)+Cl (8)
Not only does chloride ion competitively inhibit the RRCH-CR" - Pdo-2H
binding of substrates, but the remaining bound chlorides in 20
intermediate complexes diminish the electrophilicity (posi As examples, aqueous palladium(II) salts oxidize propy
tive charge density) at the palladium(II) center which drives lene to acetone (and some propionaldehyde), butenes to
the overall reaction to palladium(0). The subsequent reac methyl ethyl ketone (and some butyraldehyde), and cyclo
tion steps, hydrogen ion dissociation (reaction (9)) and hexene to cyclohexanone. Higher olefins can be oxidized by
collapse of the resulting intermediate to products (reaction 25 dioxygen using the Wacker system, but serious problems
(10)), are less favored for these chloride-bound intermediate encountered in using the Wacker system to oxidize higher
complexes that they would be for their aquated counterparts olefins have effectively prohibited any other significant
with fewer or no bound chlorides. application to manufacturing carbonyl compounds.
The rate of oxidation of the olefinic double bond by
PdCl(CH4)(HO) PdCl(CH)(OH)+H" (9)
30 aqueous palladium(II) salts generally decreases as the num
ber and/or size of hydrocarbyl substituents increases. This
PdCl(CH)(OH)--)-CHCHO--Pd-H+2 CI" (10) decrease in rate is particularly severe with PdCl in the
Wacker system, due to the competition of chloride with the
A step in reaction (10) is turnover rate-limiting for reac more weakly binding higher olefins for palladium(II) com
tion (4)in the Wacker system (reactions (7), (8), (9), and (10) 35 plexation and due to the lowered electrophilicity of multiply
give reaction (4)), so that the disfavoring influences of chloride-bound olefin-palladium(II)intermediates. Conse
chloride ion on reaction (10) and on the preceding equilibria quently, much higher palladium concentrations (with its
(7), (8), and (9) are manifested in the obtained palladium concomitant palladium investment) are necessary to obtain
catalyst activity. volumetric production rates of higher carbonyl compounds
However, the Wacker system requires a high total chloride 40 comparable to acetaldehyde production rates.
concentration to function effectively. The chloride to copper An even more prohibitive disadvantage of the Wacker
ratio must be greater than 1:1 for the copper(II) to be soluble system for manufacturing carbonyl compounds from higher
CuCi rather than insufficiently soluble copper hydroxide olefins is the substantially increased production of chlori
chlorides, and for copper(I) to be soluble CuClarather than nated organic by-products. Higher olefins are more suscep
insoluble CuCl. Moreover, in the absence of chloride, 45 tible to palladium centered oxychlorination, which chlori
aquated copper(II) is thermodynamically impotent for oxi nates not only at olefinic carbon atoms but also at allylic
dizing palladium(0) metal to aquated palladium(II). Chlo carbon atoms. Higher aldehydes and ketones having meth
ride complexation raises the copper(II)?copper(I) oxidation ylene groups adjacent to the carbonyl group are also more
potential and lowers the palladium(II)/palladium(0) oxida susceptible to cupric chloride mediated oxychlorination than
tion potential, so that at high chloride ion concentrations the 50 is acetaldehyde. As a result, the productivity of the Wacker
forward reaction (5) becomes thermodynamically favored. system for producing chlorinated organic by-products
The Wacker system has several undesirable characteris increases rapidly both with increasing number and size of
tics in the manufacture of acetaldehyde. These undesirable hydrocarbyl substituents in the olefin.
characteristics result from the high cupric chloride concen Other, multistep manufacturing processes are typically
tration. The aqueous cupric chloride solution is extremely 55 used instead of the Wacker process to convert higher olefins
corrosive; manufacturing process equipment is constructed into corresponding carbonyl compounds. For example, the
of expensive corrosion resistant materials, usually titanium. manufacture of methyl ethyl ketone (2-butanone) involves
The manufacturing processes typically convert a percent or the reaction of n-butenes with concentrated sulfuric acid to
more of the ethylene feed to chlorinated organic by-prod produce sec-butyl hydrogen sulfate and hydrolysis of sec
ucts. These chlorinated organic by-products are hygienically 60 butyl hydrogen sulfate to obtain 2-butanol and diluted
and environmentally objectionable. Their adequate separa sulfuric acid. 2-butanol is catalytically dehydrogenated to
tion from the acetaldehyde product and from other gas and produce methyl ethyl ketone. The diluted sulfuric acid must
liquid streams which exit the process and their proper be reconcentrated for recycle.
destruction or disposal add to the operating costs of the Other carbonyl compounds are instead manufactured
manufacturing processes. 65 from starting materials more expensive than the correspond
These chlorinated organic by-products have a number of ing higher olefin. For example, cyclopentanone is manufac
mechanistic origins. Some result from direct additions of tured from adipic acid instead of from cyclopentene.
 5,557,014
5 6
An effective method for the direct oxidation of higher Belgian Patent No. 828,603 and corresponding United
olefins to carbonyl compounds by dioxygen has been long Kingdom Patent No. 1,508,331 (hereafter "Matveev pat
sought in order to enable more economical manufacturing of ents') disclose a system for the liquid phase oxidation of
carbonyl compounds. Yet, in 30 years since the development olefins employing an aqueous solution combining: a) a
of the Wacker system, no alternate palladium-based system palladium compound; b) a reversible oxidant which has a
for the oxidation of olefins by dioxygen which avoids the redox potential in excess of 0.5 volt and which is a mixed
disadvantages and limitations of the Wacker system has been isopolyacid or heteropolyacid containing both molybdenum
successfully applied in commercial manufacturing opera and vanadium, or a salt of said polyacid; and, c) an organic
tion. or mineral acid other than said mixed isopolyacid or het
Systems have been proposed which use polyoxoanions, 10 eropolyacid, which organic or mineral acid is free of halide
instead of cupric chloride, in combination with palladium to ions and is unreactive (or at most weakly reactive) with the
effect the oxidation of olefins. palladium compound. The disclosed system differs from that
U.S. Pat. No. 3,485,877, assigned to Eastman Kodak of Eastman patent by simultaneously employing only certain
Company (hereafter, "Eastman patent') discloses a system heteropolyacids and mixed isopolyacids and adding certain
for converting olefins to carbonyl compounds by contacting 15 other acids to the solution. Those certain polyacids
with an agent comprising two components, one of which is employed contain both molybdenum and vanadium. Those
palladium or platinum, and the other is molybdenum triox certain other acids added are not the polyacid and are free of
ide or a heteropolyacid or salt thereof. This patent discloses halide ions.
that the so-called "contact agent' may be in an aqueous Matveev patents disclose that only the certain polyacids,
solution for a liquid phase process, but that it is advanta 20 containing both molybdenum and vanadium, function sat
geous and preferred to support the agent on a solid carder for isfactorily in the system as reversibly acting oxidants,
a vapor phase process in which gaseous olefin is contacted wherein the reduced form of the oxidant is reacted with
with the solid phase agent. The patent compares the oxida dioxygen to regenerate the oxidant. The patent further
tion of propylene with a liquid phase contact agent (in discloses that the polyacid used contains from 1 to 8
Example 16), to give acetone substantially free of by 25 vanadium atoms, more preferably 6 atoms, in a molecule
products with the oxidation of propylene in the vapor phase with molybdenum. According to the disclosure, as the
with a corresponding solid contact agent (in Example 10), to number of vanadium atoms increases from 1 to 6 the
give acrolein. Apparently, the behavior of an olefin's liquid principal characteristics of the catalyst, such as its activity,
phase reaction with the disclosed aqueous contact agent stability, and olefin capacity, increase.
solution cannot be predicted from the behavior of the 30 Matveev patents disclose typical heteropolyacids of a
olefin's vapor phase reaction with the analogous solid con formula H,PMoVOol, in which n=3+q, p=12-q, q=1 to
tact agent. 10. Matveev patents disclose that the catalyst is prepared, in
Eastman patent discloses that, when operating in the part, by dissolving in water, oxides, salts, and/or acids of the
liquid phase, heteropolyacids or their salts, and particularly elements forming the polyacid and then adding to the
phosphomolybdic acid or silicomolybdic acid in water are 35 solution, the specified other organic or mineral acid. A
preferred. Among the heteropolyacids disclosed, only phos preferred catalyst is said to be prepared by dissolving in
phomolybdic acid and silicomolybdic acid are demonstrated water NaPO (or NaHPO, or NaH2PO, or HPO, or
by working example. No salts of heteropolyacids are so POs), MoC) (or NaMoO, or H2MoC), V2O5 (or
demonstrated. Phosphomolybdovanadic acid or salts thereof NaVO), and NaCO (or NaOH) to form a solution, adding
are nowhere mentioned in this patent. 40 PdCl to the solution of molybdovanadophosphoric acid,
Eastman patent also discloses the reaction in the presence and then adding the other acid. (Sulfuric acid is the only such
of oxygen or oxygen containing gas. It also discloses peri acid demonstrated by working example.) It is said to be best
odic regeneration of the contact agent with air. However, the if the total number of Na atoms per atom of Pis not less than
use of oxygen or air is demonstrated by working examples 6. Heteropolyacids in the series designated HPMoVO
only for reactions of olefins in the vapor phase with solid 45 to HeVOao) are said to be obtained, and are said to be
phase contact agents. used in most of the working examples. (We have found that
We have found that oxygen reacts too slowly with reduced such solutions prepared according to the methods disclosed
phosphomolybdic acid or silicomolybdic acid in aqueous in Matveev patents are not actually solutions of free het
solutions for such solutions to be practically useful in the eropolyacids, as designated by formulas of the type
industrial conversion of olefins to carbonyl compounds 50 H.PMoVOao). Instead, they are solutions of sodium salts
using oxygen or air as oxidant. In contrast, our reduced of partially or completely neutralized heteropolyacids; that
polyoxoanions comprising vanadium in aqueous solution of is, solutions of sodium polyoxoanion salts.)
the present invention can react rapidly with oxygen or air. According to Matveev patents, the activity and stability of
In addition, Eastman patent discloses palladium chlorides the catalyst is increased by the presence of certain other
among various preferred palladium or platinum components 55 mineral or organic acids which do not react (or react only
for the contact agent. Palladous chloride is predominantly feebly) with palladium and contain no halide ions(e.g.
used among the working examples. Eastman patent also HSO, HNO, HPO, or CHCOOH). The most preferable
discloses that it is possible to improve the action of the of the above acids is sulfuric acid, which is said to increase
contact agent by incorporating small amounts of hydrochlo the activity and stability of the catalyst whilst not seriously
ric acid or ferric chloride. However, the only demonstration 60 increasing the corrosivity of the solution. Sulfuric acid is the
by working example adds ferric chloride in a solid phase only acid which appears in the working examples. Matveev
contact agent for a vapor phase reaction (Example 19) to patents prescribe that the amount of acid is enough to
obtain higher reaction rates (conversion and space time maintain the "pH" of the solution at "not more than 3,
yield). No such demonstration, nor result, is given for preferably at 1.0". The working examples predominantly
addition of hydrochloric acid to either a solid or a liquid 65 recite "pH' 1. Matveev patents indicate that with "higher pH
phase contact agent, nor for addition of either hydrochloric values', the catalyst is not sufficiently stable with respect to
acid or ferric chloride to a liquid phase contact agent. hydrolysis and palladium precipitation, and is of low activity
 5,557,014
7 S
in the olefinic reaction. They further indicate that with poor, especially in terms of palladium activity (see Table 1),
"lower pH values', the rate of the oxygen reaction is as to lead one away from attempting to use the example.
appreciably diminished. However, Matveev patents do not The results of selected working examples reported in
disclose any method for determining the "pH' of the dis Matveev patents are presented in Table 1. The examples
closed solutions, nor do they specify anywhere how much selected are those said to use a phosphomolybdovanadic
sulfuric acid was added to achieve the stated "pH' value. heteropolyacid in the oxidation of ethylene for which quan
The disclosure of Matveev patents is generally directed titative results are reported. Data and results to the left of the
towards providing a catalyst system having a reversibly vertical bar in Table 1 are taken directly from the patent.
acting oxidant (wherein the reduced form of the oxidant can Results to the right of the vertical bar are calculated from the
be reacted with dioxygen to regenerate the oxidant) and 10
reported results. The Example numbers are those used in
having an absence of chloride ions. Mineral acids which Belgian 828,603.
contain halide ions are specifically excluded from the certain Most working examples in Matveev patents report tests
other acids added in the disclosed system. PdCl2 is among conducted in a shaking glass reactor. Typical reaction con
the palladium compounds used in the working examples; it
is the only source of added chloride disclosed and is added 15 ditions in this reactor were 90° C. with 4.4 psi of ethylene,
only coincidental to the selection of PdCl as the palladium and separately with 4.4 psi of oxygen. Among the examples
source. PdCl and PdSO are generally disclosed to be collected in Table 1, those using the shaking glass reactor
equivalent palladium sources. with the preferred concentrations of heteropolyacid and
Matveev patents' preferred palladium concentration in the palladium (Examples 1-6) gave ethylene and oxygen rates
catalyst is said to be 0.002 g-atom/liter (2 mill/molar). This 20 of 0.089-0.156 and 0.037-0.086 (millimoles/liter)/second,
is the concentration demonstrated in most of the working respectively (see Table 1). Example 9, with 0.5g-atom/liter
examples. In Example 9 of both Belgian and British patents, PdCl2, is said to be diffusion controlled; ethylene and
a catalyst containing a very high concentration of het oxygen reaction rates were 0.223 and 0.156 (mill/moles/
eropolyacid, 1.0 g-mole/liter, and a very high concentration liter)/second, respectively.
of PdCl2, 0.5 g-atom/liter, is disclosed. This would mean 25 We have found that shaking reactors are generally poor
that 1.0 g-atom/liter chloride is added as part of the palla devices for mixing such gaseous reactants and liquid aque
dium source. The stated conclusion from this example is that ous phases and the rate diffusion (mass transfer) of gaseous
the high viscosity and specific gravity of such concentrated reactants into an aqueous catalyst solution for reaction is
solutions adversely affect the mass transfer conditions and prohibitively slow in such reactors. Additionally, 4.4 psi of
make the process diffusion controlled and impractical. The 30 ethylene is relatively too low a pressure for rapid dissolution
result reported for this test with 0.5g-atom/liter PdCl is so of ethylene into a aqueous catalyst solution.
TABLE
Examples from Belgian Patent 828,603
Reported:
CH, CH4. O
Ex. Pd Pd (HPA' HPA 76 xs temp Pch rate capacity Po, rate
No. Rctr mM source Molar Vo V. C. mmHg W' molel mmHg Wo
Sg 2 PdCl 0.3 6 25 90 230 143 0.6 230 15
2 Sg 2 PdCl 0.3 8 35 90 230 248 0.8 230
3 Sg 2 PdSO, 0.3 4 15 90 230 28 0.36 230 105
4. Sg 2 PdCl 0.3 3 O 90 230 20 0.25 230 70
5 Sg 2 PdSO 0.3 2 5 90 230 210 0.15 230 50
6 Sg 2 PdCl 0.2 6 25 90 230 90 0.3 230 60
6 SS 2 PdCl 0.2 6 25 10 6 atm 900 0.3 3.5atin 450
9 Sg 500 PdCl O 6 25 90 230 300 3.0 230 210
10 Sg 1 Pd metal 0.2 6 25 90 230 150 0.2 230 100
12 Sg 1. PdSO, 0.1 5 ? 50 230 25 0.15 230 10
Calculated:

CH Pd O
Ex. Pca, rate t.f. Pd %V Po, rate
No. psi InM/s 1/s TON red psi mM/s.
1 4.4 0.106 0.053 300 53 4.4 0.086
2 4.4 0.185 0.093 400 49 4,4 ?
3 4.4 0.095 0.048 80 52 4.4 0.078
4 4.4 0.089 0.045 25 51 4.4 0.052
5 4.4 0.156 0.078 75 48 4.4 0.037
6 4.4 0.14 0.07 50 40 4.4 0.045
6 88.2 0.670 0.335 150 40 514 0.335
9 4.4 0.223 0.0004 6 80 4.4 0.156
O 4.4 0.112 0.112 200 27 4.4 0.074
12 4.4 0.019 0.187 150 150 4.4 0.007

'All examples use solutions said adjusted to pH l with sulfuric acid, except Ex. 12 in which no sulfuric acid is added
and the pH is not reported.
Reactor type: sg. = shaking glass, ss = stainless steel (method of agitation not reported)
Palladium concentration, millimolar (mg-atom/liter)
 5,557,014
10
TABLE 1-continued
Examples from Belgian Patent 828,603
“Heteropolyacid concentration, Molar (g-mole?liter)
Heteropolyacid said to be used, according to the formula HPMoVOao), n = 3 + q p = 12 - q
Vanadium used in excess in the preparation of the HPA solution, % of q (see footnote 5)
Palladium turnover number per ethylene reaction = (CH4 capacity, moles/liter)/(Pd concentration, moles/liter)
Fraction of vanadium reduced (utilized to oxidize ethylene) in ethylene reaction = (CH, capacity, mole?)/(total V
concentration, g-atom?1)/2), where total V concentration = HPA)(q)(1 + fraction excess V used in HPA solution
preparation)
Average rate of ethylene reaction as (milliters CH at 750 mmHg, 23° C)/liter solution/minute.
'Average rate of oxygen reaction as (milliters O, at 750 mmHg, 23° C)/liter solution/minute.
'Rate of ethylene reaction as millimoles CH/liter solution/second.
'Palladium turnover frequency, {(millimoles CH/liter solution/second}lmillimolar Pd concentration.
Rate of oxygen reaction as millimoles Olliter solution/second.
15
One test in Example 6 is reported for another reactor, a tests with the preferred concentrations of heteropolyacid and
stainless steel reactor, with 88.2 psi of ethylene and with palladium and at the preferred "pH' 1 (Examples 1-6), the
51.4 psi of oxygen, each at 110° C. The method of mixing reported ethylene reaction capacities are calculated to cor
the gas and liquid phases in this reactor is not specified. respond to 40% to 53% of the oxidizing capacity of the
Example 6 also reports results with the same catalyst system 20 vanadium(V) content of the solution, assuming two vana
in the shaking glass reactor. The ethylene reaction rates were dium(V) centers are reduced-to vanadium(IV) for each
0.141 (millimoles/liter)/second in the shaking glass reactor ethylene oxidized to acetaldehyde.
and 0.670 (millimoles/liter)/second in the stainless steel Example 12 of Matveev's Belgian patent reports a test
reactor. The oxygen reaction rates were 0.045 (millimoles/ with no addition of sulfuric acid. (This result was omitted
liter)/second in the shaking glass reactor and 0.335 (milli 25 from the UK patent.) The heteropolyacid is designated
moles/liter)/second in the stainless steel reactor. Thus, the HPMooV2Oao and is used at 0.1 molar concentration
reaction rates did not increase proportionally with the pres with palladium sulfate at 0.1 mg-atom/liter concentration. A
sure when it was increased from about 4 psi to about 90 psi. "pH' for this solution is not reported. The reaction is
It is well known that the diffusion rate of a reacting gas into conducted at 50 C. On cycling between ethylene and oxygen
a liquid, as well as the gas molecule concentration in the 30 reactions, the rate of the ethylene reaction is said to diminish
liquid phase at saturation, is proportional to the partial constantly due to hydrolysis of the Pd salt. (Typical
pressure of the gas in the gas phase, all other factors being examples with sulfuric acid added, such as examples 1-6,
constant. Accordingly, the stainless steel reactor used for the were reported stable to 10 or more cycles.) This result
higher pressure test of Example 6 appears to be a poorer corresponds to Matveev's disclosure that the stability of the
device for the mixing of gas and liquid phases than the 35 catalyst is increased by sulfuric acid, that the amount of acid
shaking glass reactor used for the other tests in the Matveev is such as to maintain the "pH' at not more than 3, and that
patents. with higher "pH values the catalyst is not sufficiently stable
Typical apparent palladium turnover frequencies calcu against hydrolysis and palladium precipitation. This result
lated from ethylene reaction rates and palladium concentra reported with no addition of sulfuric acid is so poor as to lead
tions reported in Matveev patents' working examples using one away from attempting to use the example.
a shaking glass reactor are all less than 0.2 (millimoles Matveev patents also report working examples for the
CH/mg-atom Pd)/second. The higher pressure test at 110 oxidation of propylene to acetone, n-butenes to methyl ethyl
C. in a stainless steel reactor in Example 6 gave the highest ketone, and 1-hexene to methyl butyl ketone using the
apparent palladium turnover frequency of 0.335 (millimoles disclosed catalyst system. For reaction of mixtures of
CH/mg-atom Pd)/second. Although Matveev patents pur 45 n-butenes, 4.4 psi, at 90° C. in the shaking glass reactor
port that the disclosed catalysts are up to 30 to 100 times (Example 19 in Belgian 828,603; Example 16 in UK 1,508,
more active in olefin oxidation over the Wacker catalyst, the 331), the reported reaction rate is 50 (ml butenes at 750 mm
apparent activity of the palladium catalyst in the best Hg, 23° C)/liter/minute (corresponding to 0.037 (milli
example is no higher than the activity of a typical Wacker moles butenes/liter)/second) an the capacity of the reaction
palladium catalyst in typical process operation at compa 50 solution is 0.25 moles butenes/liter. The palladium concen
rable temperatures. This result is obtained even though the tration in the example is 2 mg-atom/liter: the palladium
disclosed catalyst solution is substantially free of the chlo turnover frequency is calculated 0.019 (millimoles butones/
ride ion concentration which inhibits the palladium activity mg-atom Pd)/second; the number of Pd turnovers per butene
in the Wacker catalyst. In contrast, the present invention reaction capacity is calculated 125. The fraction of the
demonstrably provides palladium catalyst activities substan 55 vanadium(V) concentration of the solution reduced by the
tially exceeding the activity of a Wacker palladium catalyst butone capacity is calculated 51%.
in typical process operation. In contrast to the teachings of the Matveev patents, we
From Matveev patents' ethylene reaction capacities and have found the following: 1) Although the Matveev patents
the palladium concentrations, the number of palladium teach that sulfuric acid increases the activity and stability of
turnovers per ethylene reaction capacity can be calculated 60 the catalyst, we have discovered that substantially increased
(see Table 1, TON). The highest number of turnovers activity (olefin and oxygen reaction rates) and stability can
obtained was 400 with the heteropolyacid containing 8 be obtained by avoiding the presence of sulfuric acid, and of
vanadium atoms (and with 35% excess vanadium present), sulfate species generally; 2) Although the Matveev patents
Example 2. teach that the rate of the oxygen reaction is appreciably
The ethylene reaction capacities of the catalyst solutions 65 diminished at pH' values lower than 1, we have discovered
of Matveev's working examples appear generally to follow that oxygen reaction rates can be obtained which are orders
the vanadium content of the solutions (see Table 1). For the of magnitude higher than those reported in the patents end
 5,557,014
11 12
which are substantially undiminished in solutions having 1 to 12x10 (moles/liter)/minute, which corresponds to
hydrogen ion concentrations greater than 0.10 mole/liter; 3) about 0.002 to 0.020 (millimoles/liter)/second; compare to
Although the Matveev patents teach that the activity and ethylene reaction rates of about 0.1-0.2 (millimoles/liter)/
stability of the catalyst all increased on increasing the second calculated from the results reported for experiments
number of vanadium atoms in the polyacid, for example at 90° C. in Matveev patents (see Table 1). The reaction rates
from 1 to 6, we have discovered that, at least in the practice reported in Kinet. Katal. 18-1 are so small as to lead one
of the present inventions, the activity (olefin and dioxygen away from attempting to use the reported reaction conditions
reaction rates) is typically invariable with the vanadium for any practical production purpose.
content of the polyacid and the stability may be decreased on Ethylene pressures for the reactions of Kinet. Katal. 18-1
increasing the vanadium content of the polyacid towards 6; 10 are not reported. The ethylene concentrations are instead
4) Although the Matveev patents teach that the total number given, but no method of either setting or determining the
of Na atoms per atom of P be not less than 6, we have found ethylene concentration is mentioned, nor is it dear whether
that with the preferred polyoxoanion-comprising catalyst these ethylene concentrations are sustained in solution under
solutions of the present invention, which optionally contain the reaction conditions.
Na countercations, the desired acidity can be obtained 15 Kinet. Katal. 18-1 states that solutions of phosphomolyb
while avoiding sulfuric acid by preferably keeping the dicvanadic heteropolyacids were synthesized by a procedure
number of Na atoms per atom of Pless than 6. described in Zh. Neorg. Khim., vol. 18 (1973), p. 413
East German Patent No. 123,085, by some of the inven (English translation edition pp. 216-219). This reference
tors of the Matveev patents, discloses a chloride-free catalyst describes making solutions from NaHPO,
for the liquid phase oxidation of ethylene to acetaldehyde 20 NaMoO-2H2O, and NaVO2H2O at “pH' 2; the method
and acetic add that consists of a solution of a palladium salt of acidification of the solutions of these basic salts, when
with an anion that does not complex palladium or does so stated, is with sulfuric acid. (This reference further mentions
only weakly and a heteropolyacid or isopolyacid or salts the isolation of crystalline vanadomolybdophosphoric acids
thereof that have a redox potential greater than 0.35 V. The via ether extraction of their ether addition compounds from
aqueous solutions disclosed in the Examples contain 2.5x 25 sulfuric acid-acidified solutions. These methods of preparing
10 mole/liter PdSO 5x10' mole/liter heteropolyacid, solution vanadomolybdophosphoric acids with sulfuric acid
(specified as HP(Mo.O.) VO, HSiCMo.O.)VO), or and crystalline products by ether extraction are also
Hs(Ge(Mo.O.)VOs), 5x10' mole/liter CuSO (omitted in described in earlier papers cited by this reference; for
Example 3), and 5x10° mole/liter NaVO, and are said to example, Inorg. Chem., 7 (1968), p. 137.) The reaction
have a "pH' of 2. Neither the method of preparation of the 30 solutions of Kinet. Katal. 18-1 are said to be prepared from
heteropolyacids in the solutions, nor the means of acidifying the solutions of phosphomolybdicvanadic heteropolyacids
the solutions to this stated "pH' is disclosed. In the by addition palladium sulfate, dilution, and adjustment of
Examples, these solutions are said to be reacted at 30° C. the "pH” by the addition of HSO, or NaOH. However, this
with ethylene at 720 mm Hg partial pressure or at 60° C. reference does not disclose the composition of the test
with ethylene at 600 mm Hg partial pressure, and with 35 solutions, in terms of the amounts of HSO or NaOH added,
oxygen at the same pressures, using a glass reactor that can nor any method for determining the "pH of the disclosed
be agitated. The greatest ethylene reaction rate disclosed is solutions.
44 ml ethylene reacted by 50 ml solution in 20 minutes at Kinet. Katal. 18-1 reports the dependence of the ethylene
60° C. with an ethylene partial pressure of 600 mm Hg, reaction rate on the solution "pH' over the stated range 0.8
corresponding to 0.021 (millimole CH/liter)/second and a 40 to 2.2, under the disclosed conditions with the heteropoly
palladium turnover frequency of 0.085 (millimole CH/mg acid designated HPMoVOol at 0.05 mole/liter, palla
atom Pd)/second. The greatest oxygen reaction rate dis dium at 3x10 g-atom/liter, ethylene at 1x10 mole/liter,
closed is 10 ml oxygen reacted by 50 ml solution in 27 and 21 C. As the "pH” is increased towards 2, the rate of the
minutes at 30° C. with an oxygen partial pressure of 720 mm ethylene reaction is shown to decrease. From evaluation of
Hg, corresponding to 0.005 (millimole O?liter)/second. 45 graphic figures in the reference, the maximum rate of
East German Patent No. 23,085 also mentions small ethylene reaction was achieved over a "pH' range of 0.8 to
additions of chloride or bromide ions act as oxidation 1.6, and corresponded to 0.023 (millimole CH/liter)/sec
accelerators and activate the catalysts, with molar ratios of ond and a palladium turnover frequency of 0.078 (mole
Pd"):(Cls 1:20 and Pd):Brs 1:5 being favorable. CH/mole palladium)/second.
The patent makes no other mention of chloride addition to 50 Matveev reviews his studies on the oxidation of ethylene
the disclosed catalyst and chloride is nowhere Indicated in to acetaldehyde in Kinetika i Kataliz, vol. 18 (1977), pp.
any of the working Examples. Instead, the title of the patent, 862-877 (English translation edition pp. 716–727; "Kinet.
the claims, and the disclosure elsewhere all explicitly Katal. 18-2'). The author states (English translation edition
specify a chloride-free catalyst. p. 722): "The chloride-free catalyst was an aqueous solution
Additional results from some of the inventors of the 55 of one of the HPA-n, acidified with H2SO to “pH' 1, in
Matveev patents are reported in Kinetika i Kataliz, vol. 18 which a nonhalide palladium salt (sulfate, acetate, etc.) was
(1977), pp. 380-386 (English translation edition pp, dissolved.” (HPA-n are defined therein as phosphomolyb
320-326, hereafter "Kinet. Katal. 18-1'). Reaction kinetic denumvanadium heteropolyacids.) Reference is then made
experiments are reported for the ethylene oxidation reaction to the studies reported in Kinet. Katal. 18-1.
with phosphomolybdicvanadic heteropolyacids in the pres 60 Reaction Kinetics and Catalysis Letters, vol 16 (1981),
ence of Pd(II) sulfate using a shaking reactor with circula pp. 383-386 reports oxidation of 1-octane to 2-octanone
tion of the gas phase. The absolute values of the observed using a catalytic system of PdSO and heteropolyacid des
reaction rates are said to be quite small, and not complicated ignated HPMoVO in a shaking glass reactor with 1 atm.
by mass-transfer processes. Most of the reported experi oxygen. The heteropolyacid is said to be synthesized as in
ments are conducted at about 20° C., and this low tempera 65 UK 1,508,331, and used as an acidic sodium salt
ture appears to be the principal reason the observed reaction NaH2PMoVO. The catalyst solution is said to have a
rates are so small. Typical reaction rates reported are about "pH” equal to 0.5-1.0, which was attained by the addition of
 5,557,014
13 14
H2SO4. However, no results are identified with any specific forms ("blues') of molybdovanadophosphate heteropolyac
pH value. Palladium is used in concentrations of -4-6 ids designated HPMo12-VnOao), n=1-4,6, containing
millimolar and PdSO is said to give a more active catalyst vanadium(IV), in aqueous solution at "pH' 3.0, in a glass
than PdCl2. The catalyst is said to have limited stability flask with magnetically-coupled stirring of the liquid phase,
above 80° C., apparently due to precipitation of palladium. at 25°C. with 2-10 kPa (0.3-1.5 psi) oxygen. Reaction rates
Ropa Uhlie 28, pp. 297-302 (1986) (Chem Abstr. are extremely slow under these low temperature, low pres
107(1):6740r) reports oxidation of 1-octene to 2-octanone sure conditions in this reaction mixing vessel. (From the
using a solution of 0.075M heteropolyacid designated data, reaction rates in the region <0.0001 (millimoles/liter)/
HPMo12.V.Oao, n=6 or 8, and containing PdSO. The second are calculated.) The oxygen reaction rates of a
heteropolyacid solution was prepared from NaH2PO, 10 reduced form of the molybdovanadophosphate n=3 were
MoO, and V2O5 in water by addition of NaOH, then measured at "pH's 2.0, 3.0, and 4.0. A maximum was
HSO, with adjustment of the stated "pH' to 1. observed at "pH' 3.0. Aqueous solutions of Nasalts of the
J. Organomet. Chem. 327 (1987) pp. C9–C14 reports heteropolyacids and the corresponding blues for the experi
oxidation of 1-octene to 2-octanone by oxygen using an ments were said to be obtained as in Izvestiya Akademi
aqueous solution of 0.12 mole/liter heteropolyacid desig 15 Nauk SSSR, Seriya Khimicheskaya, 1980, pp. 1469. This
nated HNaPMosV.O., with 0.01 mole/liter PdSO, with reference discloses that aqueous solutions of heteropolyan
various co-solvents, at 20 C., in one-stage mode. The ions were obtained by reacting stoichiometric amounts of
heteropolyacid is said to be prepared by the method HPO, MoO, and NaVO2HO with heating in the pres
described in UK 1,508,331; the “pH of the catalyst solution ence of Na2CO. (Neither the amount of NaCO added, the
is not specifically disclosed. For the reaction, 1-octene and 20 concentration of heteropolyanion, the resulting "pH's, nor
oxygen are contacted simultaneously with the catalyst solu the complete compositions of the solutions are disclosed.)
tion. The heteropolyacid cocatalyst is said to be regenerated This reference further discloses the addition of vana
by treating the aqueous solution with 1 atm. O at 75° C. dium(IV) in the form of VOSO-2HO to produce the
Reaction Kinetics and Catalysis Letters, vol 3 (1975), pp. heteropoly blues. The experimental solutions in this refer
305-310 reports the oxidation of vanadium(IV) in aqueous 25 ence are said to comprise heteropolyanion and vanadyl at
solutions of vanadyl sulfate (VOSO), 0.05–0.25 mole? "pH 1.60-2.98, buffer solution of NaHSO, and NaSO;
liter, in the "pH' region 2.5-4.5, in the presence of small neither the concentration of the buffering sulfate ions nor an
amounts of sodium molybdate in a shaker reactor, at 30 C. accounting of their origin is disclosed.
with 730 mmHg oxygen pressure. At"pH" values below 3.0 Reaction Kinetics and Catalysis Letters, vol 17 (1981),
the reaction rate is reported to decrease sharply. A het 30 pp. 401–406 reports the oxidation of vanadium(IV) in aque
eropolyacid complex of molybdenum and vanadium was ous solutions of vanadyl sulfate, 0.02-0.4 mole/liter, in the
isolated from a reaction solution. "pH' region 2.5-4.5, in the presence of smaller amounts of
Koordinatsionnaya Khimiya, vol. 3 (1977), pp. 51-58 molybdovanadophosphoric heteropolyacid designated
(English translation edition pp.39-44) reports the oxidation HPMooVOao, by the methods of Koordinatsionnaya
of reduced phosphomolybdovanadium heteropolyacids con 35 Khimiya, vol. 5 (1979), pp. 78-85. At"pH" values below 3.0
taining vanadium(IV), in aqueous solution at "pH's>1, at the reaction rate is reported to decrease sharply.
60° C. by oxygen. Heteropolyacids designated HPMo J. Chem. Soc. Dalton Trans., 1984, pp. 1223–1228 reports
nVnO), n=1-3, were said to be synthesized by the method studies of the palladium sulfate-catalyzed oxidation of
of Zh. Neorg. Khim., vol. 18 (1973), p. 413 (see above), and 1-butene to 2-butanone (methyl ethyl ketone) with phospho
a solution of the sodium salt of the heteropolyacid desig molybdovanadic acids both in the absence and in the pres
nated n=6 was said to be prepared by dissolving stoichio ence of oxygen. These studies are reported in greater detail
metric amounts of sodium phosphate, molybdate, and vana in Palladium and Heteropolyacid Catalyzed Oxidation of
date in water, boiling the solution, and acidifying it to "pH' Butene to Butanone, S. F. Davison, Ph.D. Thesis, University
1. Different "pH values for the solutions of the reduced of Sheffield, 1981. These references report, as do others loc.
forms of these heteropolyacids were said to be obtained by 45 cit., that phosphomolybdovanadic acids are extremely com
altering the initial "pH" values of the heteropolyacid solu plex mixtures of anions of the type (PMoVO".
tions, monitored by a pH meter. The acid used for acidifi Crystalline phosphomolybdovanadic acids, designated H.
cation and for altering the initial "pH values are not PMoVnO), n=1-3, prepared by the ether extraction
disclosed. Oxygen reaction rates for the reduced forms of the method of Inorg. Chem., 7 (1988), p. 137 were observed to
heteropolyacids designated n=2, 3, and 6 show maxima at 50 be mixtures which disproportionated still further in the
about "pH' 3 (at about 34x10 (mole/liter)/minute; or, 0.57 acidic media used for catalysis. Accordingly, solutions pre
(millimole/liter)/second), and decline precipitously as the pared by the method of UK 1,508,331 were chosen as
"pH' is lowered; it becomes almost negligible for n=2 at appropriate for the catalytic reactions (see Davison Thesis,
“pH 1. pp. 63 and 77), except that stoichiometric amounts of V.O.
Koordinatsionnaya Khimiya, vol. 5 (1979), pp. 78–85 55 (not excess) were used. The solutions were prepared from
(English translation edition pp. 60-66) reports the oxidation V.O.s, MoO, NaPO-12O, and NaCO, at 0.2MP, and
of Vanadium(IV) in aqueous solutions of vanadyl sulfate, acidified to "pH' 1 by addition of concentrated sulfuric acid.
0.1-0.4 mole/liter, in the "pH' region 2.5–4.5, in the pres The reactions of J. Chem. Soc. Dalton Trans., 1984, pp.
ence of smaller amounts of molybdovanadophosphoric het 1223-1228 and Davison Thesis in the absence of oxygen
eropolyacid designated HPMoVOao, in an agitated reac 60 were conducted at 20° C. and 1 atm 1-butene in a mechani
tor, at 0-30 C., by oxygen. A weak dependence of the rate cally shaken round-bottomed flask. Reactions using 5 mM
on "pH” is reported, with the rate decreasing with decreasing PdSO and 0.05M vanadium(V) in aqueous sulfuric acid
"pH” below about "pH”3.5. The addition of NaSO is said (0.03–0.2 mole/liter, depending on n) are reported to give
to have no influence on the rate of the reaction. similar initial reaction rates for n=1-7. The reactions
Izvestiya Akademi Nauk SSSR, Seriya Khimicheskaya, 65 required ca. 30 minutes for completion and gave 5 turnovers
1981, pp. 2428-2435 (English translation edition pp. on Pd (stoichiometric for two vanadium(V) reduced to
2001-2007) reports studies of the oxidation of reduced vanadium(IV) per 1-butene oxidized to 2-butanone.). A
 5,557,014
15 16
stated intention of the work was to minimize chloride U.S. Pat. Nos. 4,720,474 and 4,723,041 demonstrate by
content; PdCl is said to have similar reactivity to PdSOa. working example the oxidation of various olefins to carbo
The reactions of J. Chem. Soc. Dalton Trans., 1984, pp. nyl products: predominantly 1-hexene, as well as ethylene,
1223-1228 and Davison Thesis in the presence of oxygen 1- and 2-butenes, 4-methyl-1-pentene, cyclohexene,
were conducted at 20° C. and 1 atm of 1:l 1-butene:oxygen 1-octene, and 2-octene, all in the presence of oxygen.
in a round-bottomed flask with magnetically coupled stir Example XL gives initial olefin reaction rates using a
ring. Results are reported for the solutions used in reactions catalyst solution including Pd(NO3)2, KHPMoVOao,
in the absence of oxygen; up to about 40 turnovers on Pd and Cu(NO), with HSO added to "pH' 1.5, at 85°C. and
were obtained in about 120 minutes with the heteropolyacid 100 psig total pressure with oxygen in a stirred reactor
designated PMoV (HPMoVOol in the journal 10 without baffles. The reported ethylene reaction rate is 8.58X
account). An experiment is also reported using this het 10 moles CH/sec ml (0.858 (millimoles/liter)/second).
eropolyacid in 0.87M sulfuric acid (in the journal account it This corresponds to a palladium turnover frequency of 0.17
is cited as 1M sulfuric acid and the "pH” is stated to be ca. (millimoles CH/millimole Pd)/second. A slightly lower
-0.3.). The extra acid is said to be slightly detrimental: up to rate is reported for 1-butene.
about 32 turnovers on Pd were obtained in about 120
15
minutes. The various P-Mo-V co-catalysts are said to be
longer lasting in the "pH' range 1-2. OBJECTS OF THE INVENTION
U.S. Pat. Nos. 4,434,082; 4,448,892; 4,507,506; 4,507,
507; 4,532,362; and 4,550,212, assigned to Phillips Petro The present invention is directed towards one or more of
leum Company, disclose systems for oxidizing olefins to the following objects. It is not intended that every embodi
carbonyl compounds comprising a palladium component, a 20 ment will provide all these recited objects. Other objects and
heteropolyacid component, and additional components. U.S. advantages will become apparent from a careful reading of
Pat. Nos. 4434,082 and 4,507,507 both add a surfactant and this specification.
a diluent of two liquid phases, one of which is an aqueous An object of this invention is to provide an effective and
phase, and one of which is an organic phase. U.S. Pat. Nos. efficient process for oxidation of an olefin to a carbonyl
4,448,892 and 4,532,362 also both add a surfactant and a 25 compound. Another object of this invention is to provide a
fluorocarbon. U.S. Pat. No. 4,507,506 adds cyclic sulfones catalyst solution for oxidation of an olefin to a carbonyl
(e.g. sulfolane). U.S. Pat. No. 4,550,212 adds boric acid and compound. Another object of this invention is to provide an
optionally a surfactant. The disclosure of heteropolyacids in effective and efficient process for the preparation of catalyst
each of these patents is the same as in Matveev patents, and solutions for oxidation of an olefin to a carbonyl compound.
the heteropolyacids demonstrated by working examples are 30 A further object of this invention is to provide an effective
prepared by the same method as in Matveev patents, includ and efficient process for oxidation of an olefin to a carbonyl
ing acidification to "pH' 1.00 with sulfuric acid. PdCl is compound by one or more polyoxoanion oxidants in aque
among the palladium components exemplified. Among the ous solution, catalyzed by palladium. Another object of this
disclosed surfactants are quaternary ammonium salts and invention is to provide an effective and efficient process for
alkyl pyridinium salts, including chloride salts. However, 35 reoxidation of one or more reduced polyoxoanions in aque
cetyltrimethylammonium bromide is the only surfactant ous solution by reaction with dioxygen. Another object of
demonstrated by working example. this invention is to provide an effective and efficient process
The working examples for olefin oxidation among the for oxidation of an olefin to carbonyl compound by dioxy
above patents predominantly demonstrate the one-stage oxi gen catalyzed by palladium and one or more polyoxoanion
dation of individual n-butenes to 2-butanone in the presence 40 in aqueous solution.
of oxygen. U.S. Pat. Nos. 4,434,082 and 4,507,507 demon A further object of this invention is to provide an eco
strate oxidation of 3,3-dimethyl-1-butene and 3-methyl-1- nomically practicable catalyst solution and process for oxi
butene. U.S. Pat. Nos. 4,448,892 and 4,532,362 demonstrate dation of ethylene to acetaldehyde in an industrial acetal
the oxidation of 1-dodecene. U.S. Pat. No. 4,507,506 is dehyde plant designed to operate the Wacker process
concerned with the one-stage oxidation of long-chain alpha 45
chemistry. Another object of this invention is to provide an
olefins and demonstrates oxidations of 1-decene and economically practicable process for oxidation of an olefin,
1-dodecene.
U.S. Pat. Nos. 4,720,474 and 4,723,041, assigned to
other than ethylene, to a ketone in an industrial plant
originally designed to operate the Wacker process chemistry
Catalytica Associates, disclose systems for oxidizing olefins for the production of acetaldehyde.
to carbonyl products comprising a palladium component, a 50
polyoxoanion component, and additionally a redox active A further object of this invention is to provide an eco
metal component (certain copper, iron, and manganese salts nomically practicable catalyst solution and process for oxi
are disclosed) and/or a nitrile ligand. The disclosures empha dation of an olefin directly to a carbonyl compound, which
size the elimination of chloride from the system; the catalyst could not be so accomplished previously due to co-produc
systems do not contain chloride ions except sometimes as 55 tion of chlorinated by-products, due to reaction rates which
"only trace amounts' resulting from the presence of chloride were too slow, or due to another reason.
in the synthesis of the polyoxoanion "in order to form and A further object of this invention is to achieve any of the
(or) crystallize the desired structure'. The patents disclose above objectives with a less corrosive catalyst solution than
that "pH' or acidity can be adjusted by various proton the Wacker catalyst solution. Another object of this inven
sources, such as an acid form of a polyoxoanion or certain 60 tion is to achieve any of above objectives while minimizing
inorganic acids; sulfuric acid is said to be a preferred acid or avoiding the co-production of hygienically or environ
and is the only acid so described. The "pH' of the liquid mentally objectionable chlorinated organic by-products.
phase is said to be preferably maintained between 1 and 3 by Another object of this invention is to achieve any of the
the addition of appropriate amounts of HSO. The working above objectives in the essential absence of copper chlo
examples for olefin oxidation all add H2SO to the reaction 65 rides.
Solution, either to obtain 0.1N concentration or to obtain A further object of this invention is to achieve any of the
"pH' 1.5 or 1.6. above objectives with a higher volumetric productivity
 5,557,014
17 18
(molar amount of olefin oxidized to carbonyl product per related processes of the present invention, the aqueous
unit volume catalyst solution per unit time) than previously catalyst solution further comprises the olefin dissolved at a
disclosed catalyst systems and processes. A further object of concentration effective for maintaining the activity and
this invention is to achieve any of the above objectives with stability of the palladium catalyst for continued process
a smaller concentration or amount of palladium catalyst than operation.
previously disclosed catalyst systems and processes. In other aqueous catalyst solutions and related processes
Another object of this invention is to achieve any of the of the present invention, the solution further comprises
above objectives with greater turnovers on palladium (lesser dissolved olefin at a concentration effective for oxidizing the
Pd cost per mole carbonyl product) than previously dis olefin at a rate of at least 1 (millimole olefin/liter solution)/
closed catalyst systems and processes. Another object of this 10 second. In other processes of the present invention, the
invention is to achieve any of the above objectives with process comprises contacting the olefin with an aqueous
greater catalyst stability to long term operation than previ catalyst solution, comprising a palladium catalyst and a
ously disclosed catalyst systems and processes which avoid polyoxoacid or polyoxoanion oxidant, in mixing conditions
the use of copper chlorides. Another object of this invention sufficient for the olefin oxidation rate to be governed by the
is to achieve any of the above objectives while avoiding the 15 chemical kinetics of the catalytic reaction and not be limited
inverse squared rate inhibition by chloride ion concentration by the rate of olefin dissolution (mass transfer) into the
solution. In other aqueous catalyst solutions and related
and the inverse rate inhibition by hydrogen ion concentra processes of the present invention, the aqueous catalyst
tion which are typical of the Wacker chemistry. solution further comprises the olefin dissolved at a concen
A further object of this invention is to achieve any of the 20
tration effective for the olefin oxidation rate to be propor
above objectives with a greater effective utilization of the tional to the concentration of the palladium catalyst. In other
oxidation capacity of a vanadium(V)-containing polyoxoan aqueous catalyst solutions and related processes of the
ion oxidant solution, or greater olefin reaction capacity per present invention, the aqueous catalyst solution further
unit volume, than previously disclosed catalyst systems and comprises the olefin dissolved at a concentration effective
processes. Another object of this invention is to achieve any for providing a palladium turnover frequency of at least 1
of the above objectives with a greater volumetric reaction 25 (mole olefin/mole palladium)/second. In other aqueous cata
rate for the oxidation of vanadium(IV) to vanadium(V) by lyst solutions and related processes of the present invention,
dioxygen (molar amount of dioxygen reacted per unit vol the solution further comprises dissolved olefin at a concen
ume catalyst solution per unit time) than previously dis tration effective for oxidizing the olefin at a rate which is
closed vanadium-containing catalyst systems and processes. independent of the dissolved olefin concentration. In other
A further object of this invention is to provide an effective 30 aqueous catalyst solutions and related processes of the
and efficient process for oxidation of palladium(0), particu present invention, the aqueous catalyst solution further
larly palladium metal, to dissolved palladium(II) catalyst, in comprises the olefin dissolved at a concentration effective
for maintaining the activity and stability of the palladium
order to provide and sustain palladium catalyst activity in catalyst for continued process operation.
the inventive catalyst system. In other aqueous catalyst solutions and related processes
35
Still another object of this invention is to provide a of the present invention, the solution further comprises
method of preparing an aqueous catalyst solution suitable chloride ions. In other aqueous catalyst solutions and related
for accomplishing any of the above objectives. processes of the present invention, the solution further
comprises chloride ions at a concentration effective for
SUMMARY OF INVENTION 40
maintaining the activity and stability of the palladium cata
lyst for continued process operation. In other aqueous cata
The present invention provides aqueous catalyst solutions lyst solutions and related processes of the present invention,
useful for oxidation of olefins to carbonyl products, com the solution further comprises chloride ions at a concentra
prising a palladium catalyst and a polyoxoacid or poly tion greater than twice the concentration of palladium. In
oxoanion oxidant comprising vanadium. It also provides 45
other aqueous catalyst solutions and related processes of the
processes for oxidation of olefins to carbonyl products, present invention, the solution further comprises chloride
comprising contacting olefin with the aqueous catalyst solu ions at a concentration of at least 5 millinole per liter.
tions of the present invention. It also provides processes for Preferred aqueous catalyst solutions and related olefin
oxidation of olefins to carbonyl products by dioxygen, oxidation processes of the present invention combine the
comprising contacting olefin with the aqueous catalyst solu 50 recited features of two or more of the above mentioned
tions of the present invention, and further comprising con catalyst solutions and related processes. Especially preferred
tacting dioxygen with the aqueous catalyst solutions. are aqueous catalyst solutions and related processes which
In certain aqueous catalyst solutions and related processes combine most or all of the above features.
of the present invention, the solution has a hydrogen ion The present invention also provides processes for the
concentration greater than 0.10 mole per liter when essen 55 oxidation of vanadium(IV) to vanadium(V) comprising con
tially all of the oxidant is in its oxidized state. tacting dioxygen with an aqueous solution comprising vana
In other aqueous catalyst solutions and related processes dium and a polyoxoanion. In certain such processes of the
of the present invention, the solution is essentially free of present invention the solution has a hydrogen ion concen
mineral acids and acid anions other than of the polyoxoacid tration greater than 0.10 mole per liter when essentially all
oxidant and hydrohalic acids. In other aqueous catalyst 60 of the oxidant is in its oxidized state. In other such processes
solutions and related processes of the present invention, the of the present invention the solution is essentially free of
solution is essentially free of sulfuric acid and sulfate ions. sulfate ions. In other such processes of the present invention
In other aqueous catalyst solutions and related processes the dioxygen is mixed with the aqueous solution under
of the present invention, the solution further comprises mixing conditions effective to provide a dioxygen reaction
dissolved olefin at a concentration effective for oxidizing the 65 rate of at least 1 (millimole dioxygen/liter solution)/second.
olefin at a rate which is independent of the dissolved olefin The present invention also provides processes for the
concentration. In other aqueous catalyst solutions and oxidation of palladium(0) to palladium(II) comprising con
 5,557,014
19 20
tacting the palladium(0) with an aqueous solution compris oxidizing the olefin (reaction (14), illustrated for ethylene),
ing a polyoxoacid or polyoxoanion oxidant comprising and then reducing vanadium(V) (reaction (15)):
vanadium and chloride ions. In certain such processes of the
present invention the palladium(0) comprises palladium
metal or colloids.
The present invention also provides processes for the Pd2(V)-Pd(2V (15)
preparation of acidic aqueous solutions of salts of poly
oxoanions comprising vanadium, by dissolving oxides, Functionally, the vanadium in the polyoxoanion solution
oxoacids, and/or oxoanion salts of the component elements mediates the indirect oxidation of the reduced Pd' by
(for example: phosphorus, molybdenum, and vanadium), 10 dioxygen (reaction (15) plus reaction (13)), and functions in
and optionally carbonate, bicarbonate, hydroxide and/or a manner similar to copper chloride in the Wacker process.
oxide salts, in water, such that the resulting ratio of hydrogen We have determined that, in preferred processes of the
ions and salt countercations balancing the negative charge of present invention, under mixing conditions sufficient for the
the resulting polyoxoanions in the solution provides a hydro olefin oxidation rate to be governed by chemical kinetics
gen ion concentration greater than 10 moles/liter. 15 (not limited by the kinetics of olefin dissolution into the
We anticipate that the solutions and processes of the solution), the volumetric rate of olefin oxidation by aqueous
present invention will prove useful in oxidation processes polyoxoanion comprising vanadium(V) (reaction (12))is
other than the oxidation of olefins to carbonyl compounds, first-order dependent on (proportional to) the concentration
including, for example, oxidation of carbon monoxide, of palladium(II), and is substantially independent of the
oxidation of aromatic compounds, oxidative coupling reac 20 concentration vanadium(V). Accordingly, the oxidation of
tions, oxidative carbonylation reactions, oxidation of halides the Pd' product of reaction (14) by vanadium(V) (reaction
to halogen, and the like. (15)) is rapid relative to the rate of olefin oxidation by
palladium(II) (reaction (14)).
We discovered that the catalyst systems of the background
DETALED DESCRIPTION OF THE INVENTION 25 references discussed above become deactivated with
Empirical and Theoretical Bases for the Invention agglomeration of Pd' to colloidal palladium or even to
We have found after extensive investigations that certain
precipitated solid palladium metal. Such agglomeration and
catalyst solutions and processes discussed in the background precipitation competes with the oxidation of Pd' by vana
references are wholly impractical or practically unworkable dium(V) to regenerate the olefin-active Pd' form (reaction
for economically practicable commercial manufacture of
30 (15)). Accordingly, what would have been an originally
carbonyl products by the oxidation of olefins. Characteristic active palladium inventory would progressively accumulate
into an inactive form. For olefin oxidation in the absence of
problems we found for background catalyst solutions and dioxygen (as in equation (12)), essentially complete palla
processes using palladium and polyoxoanions include insuf dium catalyst deactivation would often occur in these ref
ficient olefin oxidation reaction rates, insufficient palladium 35 erenced processes before effective utilization of the oxidiz
catalyst activity, insufficient catalyst stability for continued ing capacity of the vanadium(V) content of the solution.
process operation, and insufficient dioxygen reaction rates. Even when most of the palladium would remain active
The following discussion outlines the results of our inves through the olefin reaction in two-stage operation with
tigations towards solving these problems and our under subsequent dioxygen reaction, multiple olefin/oxygen reac
standing of why our solutions to these problems are suc tion cycles resulted in a cumulative loss of the active
cessful. We do not intend to be bound by the following palladium catalyst concentration.
theoretical explanations since they are offered only as our The aqueous catalyst solutions of this invention have
best beliefs in furthering this art. increased stability towards deactivation because of palla
In the oxidation of olefins to carbonyl compounds by dium colloid or solid metal formation. Apparently, our
palladium catalysts and polyoxoanion oxidants comprising 45 processes more rapidly oxidize Pd with vanadium(V) (reac
vanadium, palladium appears to catalyze the oxidation of tion (15)) in competition with agglomeration of Pd into
olefins by vanadium(V) in the polyoxoanion oxidant (illus colloids or solid palladium metal, and/or they aggressively
trated in reaction (12) for ethylene oxidation to acetalde oxidize already agglomerated palladium(0) forms with
hyde), where IV and (V) represent a single vanadium(V) vanadium(V), with the result that the concentration of ole
atom and single vanadium(IV) atom in an aqueous solution 50 fin-active Pd' is maintained. Among features of the inven
of polyoxoanion oxidant, respectively: tive solutions and related processes which contribute to the
increased stability are the following: 1) hydrogen ion con
C.H., +2IV") + H.O.P's CHCHO +2IV") +2H- (12) centrations greater than 0.10 mole/liter, 2) presence of
In a subsequent step, conducted either simultaneously chloride ions, especially when above a concentration coin
(one-stage process) or sequentially (two-stage process) to 55 cidental to using PdCl2 as the palladium source, 3) concen
the above, vanadium(IV) in the polyoxoanion solution can trations of dissolved olefin effective for rapid reaction rates
be oxidized by dioxygen to regenerate vanadium(V) for the and sustained palladium catalyst activity, and 4) essential
oxidation of additional olefin: absence of sulfate ions.
The favorable influences of hydrogen ion and chloride ion
60 concentrations on catalyst stability are thought to be related,
in part, to decreasing palladium 0/II oxidation potentials,
favoring oxidation of all forms of reduced palladium to
(Reactions (12) and (13) combined give the overall reac active Pd". We have also discovered that chloride ion
tion (1) for oxidation of ethylene to acetaldehyde by dioxy catalyzes the corrosive oxidation of even solid palladium
gen.) 65 metal to soluble Pd" catalyst by polyoxoanions comprising
Palladium appears to catalyze the oxidation of olefins by vanadium(V). Accordingly, chloride ions can function to
vanadium(V) in the polyoxoanion oxidant (reaction (12)) by disfavor net accumulation of inactive colloidal and solid
 5,557,014
21 22
metallic palladium by catalyzing rapid regeneration of all inefficiently; that is, more palladium is used for the produc
forms of palladium(0) to active Pd' catalyst. A theoretical tion of a given amount of carbonyl product. Since palladium
explanation for the favorable influence of dissolved olefin is a very costly catalyst solution component, this places an
concentration on palladium catalyst stability is that dis economic burden on commercial utilization of the back
solved olefin is able to bind to the Pd product of olefin ground reference processes.
oxidation, stabilizing it in solution and thereby slowing its A convenient measure of palladium catalyst activity is the
rate of agglomeration into colloidal or metallic forms. The palladium turnover frequency, (moles olefin reacted/mole
oft-used sulfate salts may decrease ("salt-out”) olefin solu palladium)/unit time. Palladium turnover frequencies for
bility in the aqueous solution, thereby decreasing its ability ethylene oxidation determined from data presented in the
to stabilize the palladium catalyst. O background references, are substantially less than 1 (mole
In any event, we have found that, when the concentration ethylene/mole Pd)/second, often less than 0.1 (mole ethyl
of chloride ions in the solution is insufficient to otherwise ene/mole Pd)/second. Aqueous catalyst solutions and pro
maintain palladium activity, when ethylene concentration in cesses of the present invention can provide palladium turn
solution is reduced (due to low ethylene pressure in the gas over frequencies greater than 1 (mole ethylene/mole Pd)/
phase and/or due to insufficient mixing of the gas and liquid 15 second, generally greater than 10 (mole ethylene/mole Pd)/
phases such that the ethylene oxidation rate becomes limited second. Palladium turnover frequencies greater than 100
by the rate of ethylene dissolution into the solution), initial (mole ethylene/mole Pd)/second have even been achieved
palladium activity declines precipitously. We have deter with the present invention.
mined that such conditions are typical of the examples Similarly improved palladium catalyst activities are also
disclosed in Matveev patents, and contribute to their low 20 obtained for olefins other than ethylene. Each olefin will
apparent palladium catalyst activities relative to the present have its own intrinsic rate of reaction with the Pd" in a given
invention; a significant fraction of the loaded palladium aqueous catalyst solution, and these rates are influenced by
appears to reside in inactive forms. the conditions of the olefin oxidation process using the
Effective concentrations of dissolved olefin for sustaining solution. However, the relative reaction rates of different
the palladium activity may be achieved when the olefin is 25 olefins with various palladium catalyst solutions under vari
contacted with the aqueous catalyst solution in mixing ous reaction conditions generally follow the same qualitative
conditions sufficient for the olefin oxidation rate to be order.
governed by the chemical kinetics of catalysis (not limited The poor palladium catalyst activity of the catalyst sys
by the rate of ethylene diffusion into the solution), and are tems of the background references can be attributed in part
further enhanced by raising the concentration of olefin in the 30 to the extent of deactivation of the active palladium catalyst
olefinic phase (as in raising the partial pressure of gaseous into inactive forms; a fraction of the palladium load resides
olefins). Mixing conditions sufficient for the olefin oxidation in colloidal or solid metallic forms with little or no activity.
rate to be governed by the chemical kinetics of the catalytic To that extent, the features of the catalyst solutions and
reaction are established when the reaction rate is governed related processes of the present invention which contribute
by chemical characteristics of the catalyst solution, such as 35 to improved palladium catalyst stability, as recited above,
its palladium(II) catalyst concentration, and independent of also contribute to better apparent palladium catalyst activity.
moderate variations in the phase mixing efficiency. When Aqueous catalyst solutions and related processes of the
mixing conditions are insufficient, the dissolved olefin con present invention were also discovered to provide higher
centration in the bulk catalyst solution is depleted by reac intrinsic palladium(Ill activity than the catalyst systems and
tion, and the olefin oxidation rate becomes determined by 40 processes of background references. (Intrinsic palladium(Ill
the rate of dissolution (mass transfer) of the olefin into the activity can be determined by observing initial reaction rates
catalyst solution. When mixing conditions are sufficient, the under conditions when all the palladium loaded is initially
dissolved olefin concentration approaches the phase parti present as olefin-active palladium(Ill; that is, in the absence
tioning limit (the solubility of the olefin in the solution) and of any accumulation of inactive forms.) Among the features
this limit is increased in proportion to the olefin concentra 45 of the inventive solutions and related processes which
tion in the olefinic phase. For each combination of olefin, contribute to increased intrinsic palladium(II) activity are: 1)
olefin concentration in the olefinic phase, precise catalyst hydrogen ion concentrations greater than 0.10 mole/liter, 2)
solution composition, and reaction temperature, sufficient mixing conditions sufficient for the olefin oxidation rate to
mixing requirements in a given reactor device can be be governed by the chemical kinetics of the catalysis, not
established by observing reaction rates governed by chemi 50 limited by the rate of olefin dissolution into the solution, 3)
cal kinetic parameters. For ethylene, with preferred aqueous increased concentrations of dissolved olefin in solution
catalysts of the present invention, the ethylene oxidation provided by increasing its solubility (for example, by
reactor of a Wacker plant, operated at its typical pressure and increasing the pressure of gaseous olefins), and 4) essential
temperature provides sufficient concentrations of dissolved absence of sulfate ions. Surprisingly, the presence of chlo
ethylene. 55 ride ions may also contribute to higher palladium activity,
In comparison to the inventive catalyst solutions and depending on the chloride concentration and the hydrogen
processes, the catalyst systems and processes of background ion concentration. Particularly, at hydrogen ion concentra
references using catalysts comprising palladium and poly tions less than about 0.10 moles/liter, the presence of an
oxoanion components have generally poor palladium cata effective concentration of chloride ions can increase palla
lyst activity. The background references typically utilize 60 dium activity over the level with no chloride present.
much higher high palladium catalyst loadings to compensate In acidic aqueous solutions comprising palladium(II)
for low palladium activity, and even then do not report (containing no coordinating ligands or anions other than
acceptable volumetric olefin oxidation rates. A higher pal water), Pd' exists in aqueous solution predominantly as its
ladium concentration results in a lesser number of palladium hydrolytic forms: tetraaquopalladium dication, Pd(H2O).’",
turnovers (moles olefin reacted/mole palladium present) to 65 aquated palladium hydroxide, Pd(OH)2(H2O) and solid
react an amount of olefin. Accordingly, the palladium in the phase palladium oxide which may be hydrated. These forms
systems of the background references is used relatively are interconverted by the following equilibria:
 5,557,014
23 24
centration, dissolved olefin concentration, temperature, and
other reaction conditions to achieve a relatively rapid olefin
reaction. In contrast, when the reaction conditions were not
sufficient to provide such a relatively rapid olefin reaction,
the reaction rate would decelerate with vanadium(V) con
The two step-wise acid dissociation constants of reaction version, commensurate with a concomitant decrease in
16 have not been resolved (Pd'(OH)(HO) has not been hydrogen ion concentration. Apparently, when sufficient
detected), and the pKa of reaction 16, as written, is reported reaction conditions are provided for relatively rapid olefin
to be 2 in water, at or near Zero ionic strength. reaction, high vanadium(V) conversion occurs before a
We have found that, contrary to the teaching of Matveev 10 significant decrease in hydrogen ion concentration can occur
patents, the activity of the catalyst solution, specifically its by what must be relatively slow re-equilbration of the
volumetric olefin oxidation reaction rate, is independent of initially produced vanadium(IV)-polyoxoanions. In con
the vanadium content of phosphomolybdovanadate het trast, when the reaction conditions are not sufficient to
eropolyacids, when tested at the same hydrogen ion con provide relatively rapid olefin reaction, this slow re-equil
centration greater than 0.10 mole?liter, in the absence of 15 bration of the initially produced vanadium(IV)-polyoxoan
sulfuric acid and sulfate ions, under mixing conditions ions can occur while they are relatively slowly formed and
sufficient for the rate to be governed by the chemical kinetics the reaction rate decelerates concomitant with the decreasing
of catalysis. Since the chemical kinetics are first-order hydrogen ion concentration.
dependent on the concentration of the Pd', these findings Background references for the oxidation of olefins with
indicate that under these conditions, the olefin-active Pd' is 20 systems using palladium and vanadium-containing poly
not coordinated by phosphomolybdovanadate meteropolya oxoacids generally teach that PdCl and PdSO are equiva
nions (since its reactivity does not depend on the identity of lent palladium catalysts. PdSO completely ionically disso
heteropolyanions). Accordingly, it appears that under these ciates in water to sulfate ions and one or more hydrolytic
conditions, the olefin-active Pd' exists in solution as tetraa forms of Pd', as governed by hydrogen ion concentration.
quopalladium, Pd'(HO). 25 Accordingly, one would be led to conclude that when PdCl2
We further discovered that (in the effective absence of is added in the systems of the background references,
chloride ion) the rate of palladium catalyzed olefin oxidation chloride is similarly dissociated to give the same hydrolytic
in the polyoxoanion solution is highest with solutions having form(s) of Pd'. However, the background references do not
hydrogen ion concentrations greater than 0.1 mole/liter, and report the addition of chloride ions at a concentrations in
rates decrease substantially as the hydrogen ion concentra 30 excess of that coincidental to providing PdCl2. Indeed, the
tion of the solution is decreased to 0.1 mole/liter and less. background references generally promote that chloride-free
This indicates that the dicationic tetraaquopalladium, systems are most desirable. The Wacker system, with its
Pd'(HO), is the most active form of palladium(II) under higher concentrations of chloride, typically about 2 moles/
these conditions, and that as the hydrogen ion concentration liter, exhibits a severe, second order inhibition of the eth
of the solution is decreased to 0.1 mole/liter and less, an 35 ylene oxidation rate by chloride ion concentration.
increasing fraction of the palladium(II) present as Inventive aqueous catalyst solutions and related pro
Pd'(HO),' is converted to less active (lower positively cesses, by having an effective concentration of chloride ions,
charged and less electrophilic) hydroxo- and/or oxo-forms give substantially improved catalyst stability with little to
by deprotonation of coordinated water, via equilibria such as only moderate inhibition of the intrinsic Pd' activity. More
reactions (16) and (17). These hydrolytic forms are appar 40 over, since a greater fraction of loaded palladium can be
ently less active due to their lower positive charge and maintained in the active Pd' form, greater productivity can
decreased electrophilicity at Pd'. Therefore, it is quite be obtained from the total palladium load in continuous
desirable to utilize polyoxoanion solutions having hydrogen operation by the addition of an effective concentration of
ion concentrations greater than 0.10 mole/liter. chloride ions.
Hydrogen ion concentrations of polyoxoanion solutions, 45 In tested embodiments with hydrogen ion concentrations
as recited herein, refer to the hydrogen ion concentration less that 0.1 mole/liter, the presence of chloride ion at 5
when essentially all the polyoxoanion is fully oxidized, millimoles/liter does not inhibit Pd' activities to any impor
which is when essentially all the vanadium is vanadium(V). tant degree. With chloride ion at 25 millimoles/liter, Pd'
The hydrogen ion concentrations of preferred polyoxoanion activities were within 40-80% of those in the absence of
solutions often change when they are reduced, and these 50 chloride ions, and still about 100 times greater than for a
changes are not yet completely understood and predictable. typical Wacker catalyst system under comparable condi
Some solutions having hydrogen ion concentrations greater tions.
than 0.10 mole/liter when fully oxidized were discovered to Even more surprisingly discovered, as the hydrogen ion
have hydrogen ion concentrations less than even 0.01 mole? concentration is decreased below 0.1 moles/liter, a region
liter after being fully reduced by olefin oxidation. Since the 55 where Pd' activity in the absence of chloride ions decreases
theoretical equation for olefin oxidation (reaction (12)) substantially, Pd' activity in the presence of an effective
potentially adds hydrogen ions into solution, the decreased concentration of chloride ions can be substantially main
hydrogen ion concentration in these reduced solutions pre tained. Said another way, intrinsic Pd' activity in the pres
sumably results from some re-equilbration of the initially ence of chloride can exceed Pd' activity in the absence of
produced vanadium(IV)-polyoxoanion species with water 60 chloride. In tested embodiments with hydrogen ion concen
which consumes even more hydrogen ions than are poten trations about 0.01 mole/liter, Pd' activity in the presence of
tially released by reaction (12). 25 millimoles/liter chloride ion were about 5 times greater
None-the-less, olefin oxidation reactions using such an than those without chloride.
oxidized solution were found to proceed with an essentially When chloride ions are added to solutions of acidic
constant rate characteristic of the initial hydrogen ion con 65 solutions of Pd' in water, a series of aquated chloride
centration up to high conversion of the vanadium(V) when complexes are formed as the chloride ion concentration is
provided with a sufficient combination of palladium con increased. Where the acidity is such to provide Pd'(H2O)."
 5,557,014
25 26
as the hydrolytic form, the series is as follows (in each of the prise phosphorus or molybdenum. Particularly preferred
following equilibria a chloride ion is added and a water is polyoxoanions further comprise both phosphorus and
lost, to the right as written): molybdenum.
Our processes, which include reaction of preferred poly
Pd(H2O), esPdCl(HO) sPdCl(HO), PdCI,(H,O) oxoanion solutions comprising vanadium(IV) with dioxy
sPdCl (18) gen, can proceed with volumetric dioxygen reaction rates of
at least 1 (millimole dioxygen/liter solution)/second) and up
As the acidity of a solution is decreased, each of the to multiplicatively greater rates than those in background
complexes containing coordinated water can dissociate a references. Improved volumetric dioxygen reaction rates can
hydrogen ion to leave a complex of coordinated hydroxide. 10 be achieved, in part, by operating the vanadium(IV)-dioxy
With the successive replacement of coordinated water in gen reaction process under more efficient gas-liquid mixing
Pd(H2O).” by chloride ions (equation (18)), the positive conditions. It was surprisingly discovered that these even
charge on the palladium complex is decreased and the pK improved rates are still limited by the diffusion (mass
for deprotonation of remaining coordinated water is transfer) of dioxygen into the aqueous solution, so that still
increased. This increase in pK by chloride coordination 15 more rapid rates could be achieved under still more efficient
appears sufficient so that the chloro-aquo species formed in gas-liquid mixing conditions.
the presence of moderate amounts of chloride, are not The air reactors in a Wacker-type acetaldehyde manufac
significantly deprotonated to chloro-hydroxo species as the turing plant provide efficient gas-liquid mixing for achieving
hydrogen ion concentration is decreased to at least 0.01 the commercially practicable dioxygen reaction rates pro
millimoles/liter. Thereby, the Pd" catalyst activity of these 20 vided by the present invention. The dioxygen reaction rates
chloride-bound catalysts at hydrogen ion concentrations so achieved are suitable for utilization in manufacturing a
greater than 0.1 mole/liter can be substantially maintained carbonyl product using a Wacker-type manufacturing plant.
on decreasing the hydrogenion concentration to at least 0.01 We also surprisingly discovered that the presence of
millimoles/liter. Further, the chloro-aquo species appear Sulfate salts in aqueous polyoxoanion solutions, such as
substantially more active for olefin oxidation than hydroxo 25 those of background references which are prepared by
aquo species (such as Pd'(OH)2(H2O)) formed when acidification using sulfuric acid, results in slower volumetric
Pd(H2O).’" is deprotonated as the hydrogen ion concentra dioxygen reaction rates. Rates of reaction which are limited
tion is decreased towards 0.01 millimoles/liter. by diffusion (mass transfer) of a gas into a solution are a
We have also discovered that in using the inventive positive function of the solubility of the gas in the solution.
chloride-comprising catalyst solutions for the oxidation of 30 The presence of sulfate salts may decrease ("salts-out') the
olefins, chlorinated organic by-products are not formed or Solubility of dioxygen in aqueous catalyst solutions and so
are formed in amounts insignificant relative to the amounts decrease volumetric dioxygen reaction rates, but there may
formed with the Wacker catalyst system. Apparently, the be other explanations. In any case, in comparisons under the
essential absence of copper ions in preferred catalyst solu same mixing and reaction conditions, polyoxoanion solu
tions which include chloride, substantially avoids significant 35 tions comprising vanadium(IV) react with dioxygen at
oxychlorination of organics. greater volumetric reaction rates when the solution is essen
The polyoxoanion in the solutions and processes of the tially free of sulfate ions.
present invention appears to provide two functions which Background references teach that volumetric reaction
are not provided with vanadium alone in aqueous solution. rates of reduced polyoxoanion solutions with dioxygen
First, the polyoxoanion solution provides an environment decrease as the recited "pH's of solutions are decreased
for dissolution of suitably high concentrations of vanadium. towards 1. Matveev patents specifically teach that with
In acidic aqueous solutions with hydrogen ion concentra “lower pH values” (their preferred “pH” is said to be 1), the
tions comparable to preferred solutions of the present inven rate of the oxygen reaction is appreciably diminished. In
tion, vanadium(V) alone exists predominantly as the perva contrast, we have found that our solutions and processes
nadyl ion, VO"aq, whose solubility is limited; at saturation, 45 oxidize vanadium(IV) in aqueous solution by dioxygen at
it deposits solid VO. Likewise, vanadium(IV) alone exists substantially undiminished volumetric dioxygen reaction
predominantly as the vanadyl ion, VO"aq, which saturates rates over a range of hydrogen ion concentrations extending
with respect to insoluble reduced vanadium oxides. In substantially greater than 0.1 mole/liter. Consequently, We
contrast, polyoxoanions comprising vanadium can provide are able to use high hydrogen ion concentrations (e.g.
vanadium solubilities to much higher concentrations, such 50 greater than 0.1 mole/liter) to promote palladium catalyst
as the decimolar to molar level concentrations of vanadium stability and olefin oxidation activity and yet maintain
utilized in preferred solutions and processes of the present exceptional polyoxoanion oxidant regeneration rates.
inventions. Catalyst Solution and Process Description
Second, the polyoxoanion solution appears to enable The following is additional description of the aqueous
suitably rapid reaction of vanadium(IV) with oxygen, to 55 solutions of the present invention and their use in processes
regenerate vanadium(V) (reaction (13)). Although perva for the oxidation of olefins to carbonyl products:
nadyl ion is capable of palladium-catalyzed oxidation of Olefins
olefins, in a reaction similar to reaction (12), vanadyl ion Olefins suitable for oxidation according to the process of
alone reacts only very slowly with dioxygen to regenerate this invention are organic compounds having at least one
pervanadyl. In contrast, in our preferred polyoxoanion solu 60 carbon-carbon double bond, or mixtures thereof. Examples
tions, polyoxoanions comprising vanadium(IV) react very of suitable olefins are compounds represented by the for
rapidly with dioxygen, thereby providing preferred pro mula RR'C=CHR" wherein R, R', and R" each represents a
cesses of the present invention. Moreover, when hydrogen atom, a hydrocarbyl substituent, or a heteroatom
vanadyl(IV) ion is present in the polyoxoanion solution, it selected from the group halogen, oxygen, sulfur, or nitrogen,
too can react rapidly with dioxygen. Preferred polyoxoan 65 which may be the same or different, and which may be
ions comprising vanadium, which enable particularly rapid connected in one or more ring structures. Although there is
oxidation of vanadium(IV) to vanadium (V), further com no inherent limit on the size of the hydrocarbyl substituents
 5,557,014
27 28
R, R', or R", they suitably may be linear, branched, or cyclic double bond: aldehydes, ketones, carboxylic acids, and
as well as mononuclear or polynuclear aromatic. The hydro derivatives thereof. Acetaldehyde is the initial catalytic
carbyl substituents described may be C to Co, although C reaction product of ethylene oxidation. Ketones are typically
to C are especially preferred. Each hydrocarbyl substituent the initial catalytic reaction products of oxidations of higher
may also contain one or more heteroatoms of halogen, olefins. For olefins which have double-bond positional iso
oxygen, sulfur, or nitrogen. mers, mixtures of isomeric ketones may be obtained. For
The olefins themselves may be either cyclic or acyclic example, 1-hexene may yield mixtures of 2-hexanone and
compounds. If the olefin is acyclic, it can have either a linear 3-hexanone.
structure or branched structure, and the carbon-carbon The process of the present invention is highly selective to
double bond may be either terminal ("alpha-olefins') or 10 the initial catalytic reaction products (acetaldehyde and
non-terminal ("internal olefins'). If the olefin is cyclic, the ketones);they are formed with selectivities typically higher
carbon-carbon double bond may have either one, both, or than 80%, usually higher than 90%, and often higher than
neither of the carbon atoms of the double bond within the 95%. These carbonyl products may be separated in high
cycle. If the olefin contains more than one carbon-carbon yield from the reaction solution. Alternatively, the initial
double bond, the double bonds may be either conjugated or products may be further oxidized by continued exposure to
unconjugated. 15 the oxidizing reaction conditions, especially the dioxygen
Examples of suitable olefins are ethylene, propylene, reaction for regenerating the oxidant. Typically, the initial
1-butene, 2-butene (cis and trans), 1-pentene, 2-pentene, carbonyl products are oxidized to carboxylic acids by such
1-hexene, 2-hexene, 3-hexene, 1-octene, 1-decene, continued exposure. For example, acetaldehyde may be
1-dodecene, 1-hexadecene, 1-octadecene, 1-eicosene, 1-vi converted to acetic acid, and cyclohexanone may be con
nylcyclohexane, 3-methyl-1-butene, 2-methyl-2-butene, 20 verted to adipic acid.
3,3-dimethyl-1-butene, 4-methyl-1-pentene, 1,3-butadiene, Palladium Catalysts
1,3-pentadiene, 1,5-hexadiene, 1,7-octadiene, 1,9-decadi The palladium catalyst of the present invention may
ene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, comprise any palladium containing material which is suit
cyclododecene, 1,5-cyclooctadiene, 1,5,9-cyclododecatri able for oxidation of olefins under the oxidation process
ene. Preferred olefins are ethylene, propylene, 1-butene, 25 conditions. The active palladium catalyst in the solution may
cis-2-butene, trans-2-butene, 3-methyl-1-butene, 2-methyl be provided to the solution as palladium(0), for example
2-butene, 4-methyl-1-pentone, cyclopentene, and cyclohex palladium metal, or a palladium compound. Palladium(II)
ene. Mixtures of olefins may also be oxidized. Preferred salts are convenient sources of palladium catalyst. Preferred
mixtures of olefins comprise olefins which yield a common palladium(II) salts include palladium acetate
carbonyl product on oxidation, for example, mixtures of 30 (Pd(CHCO)), palladium trifluoroacetate (Pd(CFCO)),
1-butone, cis-2-butene, and/or trans-2-butene for the pro palladium nitrate (Pd(NO)), palladium sulfate (PdSO),
duction of 2 -butanone, and mixtures of 3-methyl-1-butene palladium chloride (PdCl2), disodium tetrachloropalladate
and 2-methyl-2-butene for the production of 3-methyl-2-
butanone. (NaPdCl4), dilithium tetrachloropalladate (LiPdCl), and
The olefins introduced in the process of the present dipotassium tetrachloropalladate (KPdCl4).
invention may be diluted by other compounds which are 35 It is preferred that palladium catalyst is dissolved in the
inert towards the oxidation reaction condition, for example, aqueous solution. When palladium(0) metal is the palladium
by dinitrogen, carbon dioxide, water and saturated aliphatic source, it is dissolved by oxidation to palladium(II) by the
compounds such as methane, ethane, propane, butane, polyoxoanion oxidant. This oxidative dissolution of palla
cyclohexane, and the like. For example, 1-butone, cis-2- dium(0) to give active palladium catalyst generally requires
butene, and/or trans-2-butene for the oxidation process may 40 heating of the mixture, and is accelerated in the present
be provided in admixture with butane; cyclohexene may be invention by the presence of chloride ions. Palladium(0)
provided in admixture with cyclohexane and/or benzene. may be provided as palladium metal or colloids. Palladium
With gaseous olefins, the process involves mixing a metal may be provided as bulk metal (shot, wire, foil),
gaseous olefinic phase with the aqueous catalyst solution. palladium sponge, palladium black, palladium powder, and
With olefins which are liquid under the reaction conditions, 45 the like.
the process typically involves mixing an olefinic liquid Since palladium catalyst activity depends on such factors
phase with the aqueous catalyst solution. Surfactants and/or as the identity of the olefin, olefin concentration dissolved in
cosolvents may optionally be used to increase the solubility aqueous solution, chloride ion concentration, hydrogen ion
of the olefin in the aqueous solution, or to increase the concentration, sulfate ion concentration, temperature, and
efficiency of diffusion (mass transfer) of olefins into the 50 other reaction conditions, the palladium concentration in the
aqueous catalyst solution, or both. See for example, the aqueous catalyst solution can vary in abroad range, typically
Surfactants and cosolvents disclosed in U.S. Pat. Nos. 4434, within 0.01 to 100 millimoles/liter. Although the preferred
082 and 4,507,507. Alternatively, cosolvents which misci palladium concentration will depend on other such aspects
bilize otherwise separate olefinic and aqueous phases may of the embodiment, it can be readily determined for each
be added. See for example, the cyclic sulfone cosolvents 55 application. The ratio of the molar palladium concentration
disclosed in U.S. Pat. No. 4,507,506. to the molar polyoxoanion concentration will be an effective
Dioxygen amount but less than 1. Preferred palladium concentrations
Dioxygen may be introduced into processes of the present are generally /10 to /10000 of the concentration of the
invention as oxygen, air, or mixtures thereof (enriched air). polyoxoanion. For oxidation of gaseous olefins, such as
The dioxygen may be in admixture with an inert gas, for 60 ethylene, propylene, and butenes, preferred palladium con
example, dinitrogen, carbon dioxide, water vapor. The centrations are typically 0.1 to 10 millimolar. The present
dioxygen is typically added to the process at a partial invention enables practical ethylene oxidation reactions
pressure at least equal to its partial pressure in air at one using palladium catalyst concentrations less than 1.0 milli
atmosphere pressure. molar
Carbonyl Products 65 Polyoxoanion and Polyoxoacid Oxidants
The carbonyl products of the present invention are Polyoxoanions, and corresponding polyoxoacids, utilized
organic compounds comprising at least one carbon-oxygen as oxidants in the present processes, are isopolyoxoanions
 5,557,014
29 30
and heteropolyoxoanions comprising vanadium. A treatise over these ratios are also intended. In particular, excess
on polyoxoanion compositions, structures, and chemistry is phosphoric acid or phosphate salt may be present. It is also
found in Heteropoly and Isopoly Oxometailates by M. T. intended that the Keggin phosphomolybdovanadate solu
Pope, Springer-Verlag, N.Y., 1983, which is incorporated by tions may optionally comprise excess vanadium (for
reference entirely. Polyoxoanions comprising vanadium 5 example, as VO) over the Keggin ratios.
have at least one vanadium nucleus and at least one other The net negative charge of the polyoxoanions is balanced
metal nucleus, which may be another vanadium nucleus or by countercations which are protons and/or salt cations.
any other metal nucleus which combines with vanadium in When only protons are present as countercations (when
an oxoanion composition. y=(3+x) for the Keggin phosphomolybdovanadic acid), one
Examples of suitable polyoxoanions and polyoxoacids are 10 has a "free acid' polyoxoacid. When one or more salt cations
represented by the general formula: are present as countercations, in place of protons, one has a
polyoxoanion salt, also called a salt of the polyoxoacid.
When both protons and salt cations are present, one has a
partial salt of the polyoxoacid; the free polyoxoacid is
5 partially neutralized.
wherein: Suitable salt countercations are those which are inert, or
H is proton bound to the polyoxoanion; in some way advantageous (for example, Pd(H2O).",
W is vanadium; VO), under the reaction conditions. Preferred salt coun
tercations are alkali metal cations and alkaline earth cations
O is oxygen; which do not precipitate insoluble polyoxoanion salts; for
X is selected from the group consisting of boron, silicon, example: lithium, sodium, potassium, beryllium, and mag
germanium, phosphorus, arsenic, selenium, tellurium, nesium cations, or mixtures thereof. Most preferred are
and iodine-preferably phosphorus; lithium (Li'), sodium (Na"), and magnesium (Mg') cations.
M and M' are the same or different and are independently Mixtures of Salt countercations may be present.
selected from the group consisting of tungsten, molyb 25 The Keggin phosphomolybdovanadates exist in aqueous
denum, niobium, tantalum, and rhenium-preferably at solution as equilibrium mixtures of anions varying in vana
least one of M and M' is molybdenum; dium and molybdenum content (varying in x). Moreover, for
y, a, b, c, and m are individually Zero or an integer (a is each value X such that 1CX<11, there are a number of
Zero for isopolyoxoanions and mixed isopolyoxoan positional isomers for the placement of the vanadium and
ions, or a is an integer for heteropolyoxoanions); 30 molybdenum in the Keggin structure:for x=2 there are five
X, and Z are integers; and, isomers, for x=3 there are 13 isomers, for x=4 there are 27
b+c+x is greater than or equal to 2. isomers, and so on. Each of these compositional and iso
Preferred polyoxoanions are the so-called Keggin het meric species has its own acid dissociation constants which
eropolyoxoanions represented by the above general formula, determine the extent to which it is protonated at a given
additionally defined wherein: 35 hydrogen ion concentration is solution. (That is, each com
positional and isomeric species can have its own average y
a is one, value in a given solution.) Accordingly, the compositions of
b+c+x is 12; aqueous Keggin phosphomolybdovanadate solutions are not
z is 40. generally easily characterized in terms of a their component
Most preferred are Keggin heteropolyoxoanions and het 40 species (HPMoV.O.) and their individual
eropolyacids comprising phosphorus, molybdenum, and COICetations.
vanadium (phosphomolybdovanadates), represented by the The present inventors have adopted a simplified, yet
following formula when in the oxidized state: definitive, method of designating the elemental constitution
of solutions containing Keggin phosphomolybdovanadate
45 free acids or alkali metal salts in the oxidized state, in terms
(HPMoa)V.O.) of the general formula:
wherein:
X and y are integers;
50 wherein:
More specifically, 0sys(3+x) for polyoxoanion species A is an alkali metal cation (Li, Na');
and 0Sys(3+x) for polyoxoacid species. Except when a the designated concentration of the solution is its phos
polyoxo species is completely deprotonated (i.e., y=0) or phorus concentration, usually reported in moles/liter
completely protonated (i.e., y=(3+x)), it is both a polyoxoan 55 (molar, M);
ion species and a polyoxoacid species. However, protons phosphorus, molybdenum, and vanadium are present in
dissociated into solution may also be considered in desig the concentration ratios defined by n, and 0<ng12;
nating a solution as comprising a polyoxoacid, even though alkali metal is present in solution in a concentration ratio
all the polyoxo species present may be fully deprotonated in to phosphorus defined by p, and 0Sps (3+n).
the solution. The Keggin phosphomolybdovanadates have 60 Accordingly, the negative charge of the designated Keggin
been found to be anions of very strong acids, and are formula in fully deprotonated form, 3+n, is balanced in
believed never to be fully protonated in aqueous solution. solution by phq monocations. Since this designation refers
Preferred phosphomolybdovanadate solutions have phos to a mixture of polyoxoanions, n and p may be non-integral.
phorus, molybdenum, and vanadium present in relative This designation completely defines the elemental con
molar amounts approximating the composition of the Keg 65 stitution of an aqueous solution. A given elemental consti
gin heteropolyoxoanions; that is (MoH-IV)212(P). How tution will have one thermodynamic equilibrium distribution
ever, solutions having an excess of one or two components of species comprising its component elements. When the
 5,557,014
31 32
phosphorus, molybdenum, and vanadium in these solutions The temperature of the preparation process may be within
are predominantly present in Keggin heteropolyanions of the range 50° to 120°C. It is most conveniently operated in
formula (HPMoV.O. (which is usually the boiling water at about 100° C.
case in the preferred solutions of the present invention), then Typically, a solution of alkali vanadate, for example
n is approximately equal to the average value of X among the 5 sodium metavanadate (NaVO) or hexasodium decavana
distribution of species. The concentration of free hydrogen date (NaVO), is prepared in water. This solution can be
ions in such a solution is approximately the concentration of prepared by dissolving solid salts into water, but is prepared
phosphorus multiplied by the difference between p and the most economically by adding alkali carbonate (e.g.
average value of y among the distribution of species. When NaCO), alkali bicarbonate (e.g. NaHCO), or alkali
the phosphomolybdovanadates are the only acids in solu O hydroxide (e.g. NaOH) to a suspension of vanadium oxide
tion, the acidity of the solution can be set by the phospho (VO) in water and heating to complete the reactive dis
molybdovanadate concentration, its identity (n), and the solution. Then, molybdenum oxide and phosphoric acid (or
ratio of alkalications (p) to hydrogen ions (3+n-p). alkali phosphate salt) are added to the alkali vanadate
Preferred phosphomolybdovanadate solutions following
this method of designation have 0<n<12. Especially pre solution and heating is continued to complete the prepara
ferred solutions have 2<nk6. 15 tion of an acidic aqueous phosphomolybdovanadate salt
The concentration of the polyoxoanion can be varied over solution. Finally, the solution is adjusted to the desired
a broad range, typically within 0.001 to 1.0 moles/liter. concentration by evaporation and/or volumetric dilution.
Preferred concentrations depend strongly on the composi Additional basic alkali salt (carbonate, bicarbonate, of
tion of the polyoxoanion, the specific application, and the hydroxide) can be added at any point during or after the
reaction conditions. For oxidation of gaseous olefins, such as 20 preparation to further neutralize the resulting polyoxoacid
ethylene, propylene, and butenes, preferred polyoxoanion solution and obtain decreased acidity; that is, to adjust the
concentrations are typically 0.1 to 1.0 molar. value p in the designation {AHPMo12 VnOao.
The polyoxoanions can be provided to the aqueous cata When solutions having the same phosphorus concentra
lyst solution by dissolving prepared polyoxoanion solids tion and vanadium content, n, but different acidities (differ
(free acids or salts) or by synthesis of the polyoxoanion 25 ent p) are already prepared and available, solutions of
directly in the aqueous solution from component elemental intermediate acidity (intermediate p) can be prepared by
precursors. Suitable polyoxoanion solids and polyoxoanion blending the available solutions in the appropriate volumet
solutions can be prepared by methods in the art, such as in ric ratios. More generally, solutions of determinate compo
the background references cited in the section Background sition can be prepared by blending measured volumes of two
of the Invention. For those solutions and related processes of 30 or more solutions, of known phosphorus concentration,
the present invention which are not required to be essentially vanadium content (n), and salt cation content (p).
free of sulfate ions, the polyoxoanion may be prepared by Hydrogen Ions
the methods which add sulfuric acid in the aqueous solution. Hydrogen ions and hydrogen ion concentrations, as used
U.S. Pat. No. 4,146,574, incorporated by reference entirely, herein, have their usual meaning. Hydrogen ions in aqueous
teaches a method for the preparation of solutions consisting 35 Solution are free, aquated protons. Hydrogen ion concentra
of free phosphomolybdovanadic acids. tion is not meant to include protons bound in other solute
Alternatively, the present invention provides a process for species, such as in partially protonated polyoxoanions or
the direct preparation of acidic aqueous solutions of salts of bisulfate.
polyoxoacids comprising vanadium without the introduction Hydrogen ions may be provided by providing an acid
of mineral acids other than the polyoxoacid or its component 40 which dissociates protons when dissolved in aqueous solu
oxoacids. The acidity of the resulting solutions is readily tion. Organic and mineral acids which are sufficiently acidic
adjusted by the balance of salt cations and protons in the salt. to provide the desired hydrogen ion concentration are suit
Process for the Preparation of Polyoxoanion Solutions able. The acid is preferably inert to oxidation and oxidative
According to the present invention, acidic aqueous solu destruction under intended process conditions. Acid anhy
tions of salts of polyoxoanions comprising vanadium are 45 drides and other materials which hydrolytically release
prepared by dissolving in water oxides, oxoacids, and/or protons on reaction with water may likewise be used to
salts of oxoanions of the component polyoxoanion elements, provide hydrogen ions.
and optionally salts of carbonate, bicarbonate, hydroxide, Strong mineral acids, such as polyoxoacids, sulfuric acid,
and oxide, such that the resulting ratio of protons and salt hydrochloric acid, and the like, are preferred sources of
countercations balancing the net negative charge of the 50 hydrogen ions. Particularly preferred are polyoxoacids. Cer
resulting polyoxoanions in the solution provides a hydrogen tain solutions and related processes of the present invention
ion concentration in solution greater than 10 moles/liter, are essentially free of sulfuric acid. Certain solutions and
Preferably, the resulting hydrogen ion concentration is related processes of the present invention are essentially free
greater than 10 moles/liter, and most preferably, greater of mineral acids other than of polyoxoacids and hydrohalic
than 0.1 moles/liter. 55 acids.
Preferred Keggin phosphomolybdovanadate salts are Hydrogen ion concentrations of polyoxoanion solutions,
preferably prepared in solution by dissolving vanadium as recited herein, refer to the hydrogen ion concentration
oxide and/or vanadate salt, molybdenum oxide and/or when essentially all the polyoxoanion is in its fully oxidized
molybdate salt, phosphoric acid and/or phosphate salt, and state, which is when essentially all the vanadium in the
optionally carbonate, bicarbonate, and/or hydroxide salt in 60 polyoxoanion solution is in the vanadium(V) state. It has
water, such that the ratio of protons (3+n-p) and other salt been determined that the acidity of the preferred polyoxoan
countercations (p) balancing the negative charge of the ion solutions change with reduction, and these changes are
phosphomolybdovanadates (3+n)in the solution provides the not yet completely understood and predictable. (For
desired hydrogen ion concentration in the solution. Prefer example, 0.30M (NaHPMoVO solution has a hydro
ably the vanadium, molybdenum, and phosphorus reactants 65 gen ion concentration greater than 0.10 moles/liter in equili
are added in ratios corresponding to the desired average brated fully oxidized state, but less than 0.01 moles/liter in
Keggin composition of the solution. equilibrated fully reduced state, when all the vanadium is in
 5,557,014
33 34
the vanadium(V) state.) The preferred polyoxoanions of the Sulfate Ions
present invention are most readily prepared essentially fully Sulfate ions, as used herein, is meant to include both
oxidized, and can be readily returned to that condition by sulfate dianion (SO) and bisulfate anion (HSO). Since
reaction with dioxygen according to processes of the present sulfuric acid is a very strong acid, addition of sulfuric acid
invention. In the context of determining hydrogen ion con to an aqueous solution results in a solution of sulfate and/or
centrations, the phrase "when essentially all the oxidant is in bisulfate ions, depending on the acidity of the solution.
its oxidized state' means when the solution of oxidant is Certain solutions and related processes of the present
sufficiently oxidized so as to have the hydrogen ion con invention are 'essentially free of sulfate ions'. This means
centration which is obtained when it is fully oxidized. the concentration of sulfate and/or bisulfate salts is suffi
The hydrogen ion concentration is sufficient to provide an 10 ciently low so that their undesired influence on palladium
acidic solution having a hydrogen ion concentration greater catalyst activity, palladium catalyst stability, volumetric
than 10 mole/liter. Preferably, the hydrogen ion concen olefin oxidation rate, or volumetric dioxygen reaction rate is
tration is greater than 10 moles/liter, and most preferably, not significantly manifested. This can be readily determined
greater than 0.1 moles/liter. Certain solutions and related experimentally. Preferably, these solutions are free of sulfate
processes of the present invention specifically comprise 15 and/or bisulfate salts.
hydrogen ions at a concentration greater than 0.1 mole per Chloride Ions
liter of solution when essentially all the oxidant is in its Chloride ions can be provided by any chloride-containing
oxidized state. compound which readily dissolves in water, or reacts with
Hydrogen Ion Concentration Measurement water, to release free, aquated chloride ions into solution.
Background references for polyoxoanion solutions gen 20 Suitable chloride-containing compounds include hydrochlo
erally recite "pH' values for the solution but do not specify ric acid, chlorides and oxychlorides of oxoanion-forming
methods for determining them. pH is technically defined as elements, chloride complexes and chloride salts, and the
-logart), where at is the hydrogen ion activity. The like. Examples of chlorides and oxychlorides of the oxoan
hydrogen ion activity is identical to the hydrogen ion ion-forming elements are PCls, POCl, VOCl, VOCl,
concentration in otherwise pure water. The hydrogen ion 25 MoOCl, and the like. Suitable chloride salt countercations
activity and hydrogen ion concentration are still good are those which are inert, or in some way advantageous (for
approximations of each other in aqueous solutions which are example, Pd"), under the reaction conditions and which do
low in ionic strength and otherwise approximately ideal. not precipitate insoluble polyoxoanion salts out of aqueous
Solutions of polyoxoacids at decimolar concentrations, typi solution. Preferred chloride-containing compounds are
cal in background references and in the present invention, 30 hydrochloric acid, palladium chloride compounds, and chlo
have high ionic strength and are very non-ideal solutions, ride salts of alkali metal cations and alkaline earth cations
especially when they also contain high concentrations of which do not precipitate insoluble polyoxoanion salts.
other mineral acid salts. Examples of suitable palladium chloride compounds are
The common method to obtain pH measurements of PdCl2, NaPdCl4, KPdCl4, and the like. Examples of suit
aqueous solutions uses pH-sensitive glass electrodes, moni 35 able alkali and alkaline earth salts are lithium chloride
tored with an electrometer (a "pH meter'). Such electrodes (LiCl), sodium chloride (NaCl), potassium chloride (KCl),
are known to exhibit an "acid error', measuring increasingly and magnesium chloride (MgCl2).
incorrect "pH's as pH is decreased below 2 and especially Significant amounts of chloride may also be present as
at real pH 1 and below. Moreover, successful measurement impurities in the starting materials for polyoxoanion prepa
at any pH level requires calibration with solutions of similar 40 ration. For example, we surprisingly discovered that several
ionic media and ionic strength. Common calibration solu commercial sources of sodium vanadate are sufficiently
tions for pH meters are at relatively low ionic strength and contaminated with chloride to provide effective amounts of
of very different ionic media compared to decimolar poly chloride in polyoxoanion solutions prepared from them.
oxoanion salt solutions. We have found that using different Certain solutions and related processes of the present
common calibration solutions can lead to different "pH' 45 invention comprise chloride at concentrations greater than
measurements for the same polyoxoanion solution. Unless a coincidental to using PdCl as the palladium source; that is
disclosure contains a recitation of the method of "pH' greater than twice the palladium concentration. Preferably,
measurement for these solutions, including the methods of the chloride concentration is greater than four times the
calibration, one having ordinary skill does not know what a palladium concentration. Most preferably, the chloride con
reported "pH' value really means, nor how to reproduce it. 50 centration is at least 5 millimolar. There is no particular
We have developed a more definitive method of measur upper limit on the chloride concentration, but is preferably
ing hydrogen ion concentration in the polyoxoanion solu less than a concentration at which the palladium catalyst
tions of the present invention. It is based on the observation activity becomes inversely dependent on the square of the
(by 'P- and V-NMR studies) that in solutions designated chloride concentration. Chloride is usually present at a
{AHPMoVOao, PMoVOao is essentially the 55 concentration of 0.001 to 1.0 moles/liter, preferably 0.005 to
only species present. It was further determined that 0.50 moles per liter, and most preferably 0.010 to 0.100
PMoVO, remains completely unprotonated even in moles per liter. Typically, the chloride is present in milli
concentrated solutions (>0.3M) of the free acid molar to centimolar concentrations, where unquantified
{HPMoVO}. (Species having two or more vanadia do "millimolar concentrations' refers to concentrations of 1.0
become protonated in acidic aqueous solutions.) Accord 60 to 10.0 millimolar, and unquantified "centimolar concentra
ingly, for solutions of {AHPMoVOao, the hydrogen tions' refers to concentrations of 10.0 to 100.0 millimolar.
ion concentration is the phosphorus concentration multiplied Generally, the chloride is present in these solutions at a
by (4-p). Such solutions were prepared and used to calibrate molar ratio of 10/1 to 10,000/1 relative to palladium.
glass pH electrodes for measurement of the hydrogen ion Chloride may also be provided by copper chlorides, for
concentration of solutions of undetermined acidity, having 65 example by residual Wacker catalyst retained in an industrial
the same phosphorus concentration. This method is illus plant designed to operate the Wacker process chemistry after
trated in the examples. draining the Wacker catalyst solution. However, the chlo
 5,557,014
35 36
ride-containing solutions and related processes of the For dioxygen reaction processes, elevated partial pressure
present invention are preferably essentially free of copper is usually utilized to increase the concentration of oxygen in
ions. "Essentially free of copper ions' means the olefin the gas phase in contact with the liquid phase, to increase
oxidation process with the solution does not produce sub reaction rates and decrease reactor volumes. Generally,
stantially higher amounts of chlorinated organic by-products oxygen is reacted at partial pressures of 0.2 atmosphere (1
than a corresponding solution which is free of copper ions. atmosphere air) to 100 atmospheres, typically in the range
Process Conditions 0.2 atmospheres to 20 atmospheres, and preferably in the
Broadly, olefin oxidation processes of the present reaction range 1 atmosphere (about 15 psi) to 10 atmosphere (about
are conducted under oxidative conditions sufficient to oxi 150 psi).
dize the olefin to a carbonyl product. Likewise, in processes 10 For oxidation of gaseous olefins by dioxygen in two stage
involving reaction of dioxygen, the dioxygen reaction is mode, the total pressures in the olefin reactor and the
conducted under oxidative conditions sufficient to utilize dioxygen reactor are typically similar, but may be varied
dioxygen to oxidize the olefin, or intermediately, to regen independently. In two stage mode, compressed air is typi
erate the polyoxoanion oxidant in its oxidized state. cally used, but oxygen could be used as well.
The preferred temperature range for processes of the 15 For oxidation of gaseous olefins by dioxygen in one-stage
present invention varies with the identity of the olefin and is mode, oxygen is typically used and olefin and oxygen are
interdependent with such factors as the olefin concentration typically fed in near stoichiometric ratios, about 2:1.
in aqueous solution, chloride ion concentration, palladium Liquid olefins can be reacted neat or in combination with
concentration, and other factors which determine reaction substantially inert diluents. Generally, the concentration of
rates. Increasing temperature generally provides increased 20 the liquid olefin in a second liquid olefinic phase is increased
reaction rates, although these increases are slight for reac to increase reaction rates and decrease reactor volumes.
tions which are limited by diffusion. In some cases, lower However, in some applications, it may be advantageous to
temperatures may be preferred to avoid troublesome side use a diluent. Such diluent may improve the mixing and
reactions. In two-stage operation, temperatures for the olefin mass transfer of the olefin into the aqueous catalyst solution,
reaction and the dioxygen reaction can be set independently. 25 or provide improved recovery of the carbonyl product by
Generally, temperatures utilized in processes of the present improved liquid-liquid phase distribution, and/or improved
invention may range from about 20° to about 200 C., phase separation. In other applications, the olefinic feed may
usually in the range 60° to 160° C. For gaseous olefins, such be obtained in combination with substantially inert diluents
as ethylene, propylene, and butenes, the temperature is which are more easily or economically separated from the
preferably in the range 90° to 130° C. 30 carbonyl product than from the olefin. For example, butenes
Pressures for the processes of the present invention may be obtained in combination with butane, cyclohexene
depend strongly on the nature of the olefin, whether gaseous may be obtained in combination with cyclohexane and/or
or liquid under the reaction conditions, whether dioxygen benzene. In other applications, it may be desirable to use a
reaction is conducted simultaneously or separately with the cosolvent diluent which miscibilizes the olefinic and aque
olefin oxidation reaction, whether oxygen is added as oxy 35 ous solution components.
gen or air, and reaction temperatures. For example, at Suitable reactors for the processes of the invention pro
reaction temperatures less than 100° C., the atmospheric vide for efficient mixing of olefinic and aqueous catalyst
boiling point of water, with olefins which are liquid under phases. Efficient mixing in the olefin reaction is established
the reaction conditions, in the absence of dioxygen, the when the rate of the reaction is governed by the chemical
olefin oxidation process may be conveniently conducted at 40 kinetics of catalysis, and is not limited by diffusion of the
atmospheric pressure. For temperatures near or above 100 olefin into the aqueous phase. Once that condition is estab
C. and above, water vapor contributes significantly to the lished, dissolved olefin concentration in the aqueous solu
total pressure in the reactor device. tion can be increased by increasing the olefin concentration
For gaseous olefins, elevated partial pressure is usually in the olefinic phase (for gaseous olefins, by increasing the
utilized to increase the concentration of olefin in the gas 45 partial pressure of the olefin). In some embodiments, the
phase in contact with the liquid phase, and thereby increase olefin concentration in the aqueous solution is effective for
its solubility in the liquid phase, to increase reaction rates the olefin oxidation rate to become independent of the olefin
and decrease reactor volumes. Generally, gaseous olefins are concentration in the aqueous solution (olefin saturation
reacted at partial pressures of 1 atmosphere to 100 atmo kinetics). Efficient mixing in the dioxygen reaction is estab
spheres, typically in the range 4 atmospheres (about 60 psi) 50 lished when the diffusion-limited dioxygen reaction rate
to 20 atmospheres (about 300 psi). In two-stage mode, proceeds rapidly enough for convenient and economical
gaseous olefins are preferably reacted at partial pressures in utilization in the intended application, preferably at least 1
the range of 8 atmospheres (about 120 psi) to 12 atmo (millimole dioxygen/liter solution )/second.
spheres (about 80 psi). Reactors and associated equipment in contact with the
In certain solutions and processes of the present inven 55 aqueous catalyst solution should withstand the oxidizing
tion, olefin is dissolved in the catalyst solution at concen nature of the solution and processes without corrosion. For
trations effective for its rate of oxidation to be at least 1 solutions and processes in the absence of chloride, stainless
(millimole olefin/liter solution)/second, or at concentrations steel, Hastelloy C. glass, and titanium provide suitable
effective to provide a palladium turnover frequency of at equipment surfaces. For solutions and processes in the
least 1 (mole olefin/mole palladium)/second, or preferably 60 presence of chloride, titanium and/or glass is preferred.
both. Reaction conditions and mixing conditions which meet The carbonyl product of the reaction may be separated
these criteria can be established by routine experimentation, from the reaction solution by usual methods such as vapor
for example using the procedures of the following izing ("flashing' by pressure drop), stripping, distilling,
Examples. In certain solutions and processes of the present phase separation, extraction, and the like. It is preferred that
invention, the olefin is dissolved at concentrations such that 65 the carbonyl product is recovered while leaving the aqueous
its rate of oxidation is not further increased by further solution in a form suitable to use directly in continued
increasing its concentration (olefin saturation kinetics). process operation. In two-stage operation, it is preferred to
 5,557,014
37 38
remove the product before the dioxygen reaction. In one liter)in solutions of 0.30M {NaHs PMooVOao reacted
stage operation for a volatile carbonyl product, it is preferred at 120° C. with ethylene at 150 psi partial pressure. The
to continuously remove the product as it is formed in the number next to each data point is the number of the
process. corresponding Example which follows.
Processes for the oxidation of palladium(0) to palla FIG. 2 is a scatter plot of ethylene reaction rates vs.
dium(II) require only that the palladium(0) is contacted with palladium catalyst concentrations measured using 0.30M
the polyoxoanion oxidant solution under conditions suffi {LiHPMoVO} reacted at 115° C. with ethylene at 150
cient to oxidize palladium(0) to palladium(II) at the desired psi partial pressure. The data points correspond to Examples
rate. Temperature, chloride ion concentration, and palla 32-35 (Table 2) which follow.
dium(0) surface area are particularly interdependent in 0
FIG. 3 is a scatter plot of dioxygen reaction rates vs.
determining such conditions. Generally, the greater the impeller stirring rates measured for vanadium(IV)-poly
chloride ion concentrations, the lower the temperature oxoanion solutions in each of three stirred tank autoclave
required to achieve a desired rate. If the dissolved palla reactor configurations under different reaction conditions.
dium(II) is to be used in an olefin oxidation process, the Within each data series, the vanadium(IV)-polyoxoanion
conditions are generally similar to those of the olefin oxi 15
solution, the partial pressure of dioxygen, and the reaction
dation process. temperature were the same. The three data series correspond
Solutions and Processes Wherein the Hydrogen Ion Con to Examples 58 (Table 6), 59 (Table 7), and 60 (Table 8)
centration is Greater Than 0.1 Mole/Liter which follow.
Solutions and related processes of the present invention
wherein the hydrogen ion concentration is greater than 0.1 20
EXAMPLES
mole/liter need not be essentially free of sulfate, nor further
comprise chloride ions, nor further comprise any minimum Without further elaboration, it is believed that one skilled
dissolved olefin concentration. However, preferred embodi in the art can, using the preceding description, utilize the
ments of such solutions and processes may include one or present invention to its fullest extent. The following specific
more of these features. 25 examples are, therefore, intended to be merely illustrative,
Solutions and Processes Essentially Free of Sulfate and not limitative of the disclosure in any way whatsoever.
Solutions and related processes of the present invention Further exemplification is provided in patent application Ser.
which are essentially free of sulfate ions need not also Nos. 07/934,643, and 07/675,937, now abandoned, each of
comprise a hydrogen ion concentration greater than 0.1 which is incorporated by reference entirely.
mole/liter, nor further comprise chloride ions, nor further 30 Every -logH value recited in these examples and in the
comprise any minimum dissolved olefin concentration. drawings is the base 10 logarithm of the hydrogen ion
However, preferred embodiments of such solutions and concentration in units of mole/liter. Thus, -logH)=1.0
processes may include one or more of these features. In corresponds to a hydrogen ion concentration of 0.10 mole/
particular, it is preferred that the hydrogen ion concentration liter, and a -logH"<1.0 corresponds to a hydrogen ion
of the solution be at least greater than 10 moles/liter. 35 concentration greater than 0.10 mole/liter
Solutions and Processes Comprising Chloride Preparations of Polyoxoanion Solutions
Solutions and related processes of the present invention Examples 1 through 8 and 10 through 31 show prepara
using those solutions which comprise chloride ions need not tions of solutions of polyoxoanions within the scope of the
also comprise a hydrogen ion concentration greater than 0.1
mole/liter, nor also be essentially free of sulfate, nor further 40 invention which are useful in the inventive catalyst solutions
comprise any minimum dissolved olefin concentration. and processes. Except when otherwise stated, the exempli
However, preferred embodiments of such solutions and fied polyoxoanion syntheses from HPO, MoC), and V.O.
processes may use one or more of these features. In par were conducted in a 3 neck Morton flask, of 5.0 liter or 12.0
ticular, it is preferred that the hydrogen ion concentration of liter capacity, equipped with an electric heating mantle, an
the solution be at least greater than 10 moles/liter. 45 efficient reflux condenser/demister, a powder addition funnel
It is especially preferred that solutions and processes and a high torque overhead mechanical stirrer. Distilled
which do not provide effective concentrations of dissolved water rinses were used for every solution transfer in the
olefin, do comprise chloride ions. preparations to ensure essentially quantitative recovery of
Solutions and Processes Comprising Dissolved Olefin at dissolved solution components in the final solution.
Effective Concentrations 50 Examples 1 through 8 illustrate preparations of the Keg
Solutions and related processes of the present invention gin polyoxoanion PMoVO in solutions designated
which comprise certain effective dissolved olefin concen {AHPMoVOao, which are particularly useful as
trations in the aqueous catalyst solution, and processes calibration standards for the determination of hydrogen ion
which comprise certain effective mixing conditions need not concentrations in the inventive catalyst solutions.
also comprise a hydrogen ion concentration greater than 0.1 55
mole/liter, nor be essentially free of sulfate, nor further Example 1
comprise chloride ions. However, preferred embodiments of Preparation of 0.30M HPMoVO}
such solutions and processes include one or more of these An aqueous solution of the phosphomolybdovanadic free
features. In particular, it is preferred that the hydrogen ion acid H.PMoVO was prepared according to the following
concentration of the solution be at least greater than 10 60
reaction equation:
moles/liter.

BRIEF DESCRIPTION OF THE DRAWENGS 0.5 V,Os-11 MoO+HPO+0.5 HO-HPMoVOo(aq)

FIG. 1 is a scatter plot of measured palladium catalyst 65 45.47 grams granular V.O. (0.25 mole) and 791.67 grams
turnover frequencies vs. -logH) (the negative base 10 MoO (5.50 mole) were suspended in 5.0 liters distilled
logarithm of the hydrogen ion concentration in moles per water with moderate stirring. 57.37 grams 85.4% (w/w)
 5,557,014
39 40
H.PO (0.50 mole) was added, the mixture was diluted to a sociated, with release of hydrogen ions from water, at
total volume of 10.0 liters with an additional 4.5 liters of equilibrium. 162 MHz P-NMR and 105 MHz V-NMR
distilled water, and the mixture was heated to reflux. After 2 spectra of these solutions were essentially identical to those
days at reflux, 15 drops of 30% HO was added dropwise of 0.30M {HPMoVO, showing substantially only the
to the mixture. The mixture was maintained at reflux for a PMoVO ion.
total of 7 days, giving a slightly turbid light burgundy-red
mixture. The mixture was cooled to room temperature and Examples 4-8
clarified by vacuum filtration. The volume of the solution Preparations of 0.30M {AHPMoVOao}, A=Na, Li
was reduced to about 1.5 liters by rotating-film evaporation
at 50° C. under vacuum. The resulting homogenous, clear, 10 The following 0.30M {AHPMoVOo solutions
burgundy-red solution was volumetrically diluted with dis were prepared by blending 0.30M {HPMoVOao
tilled water to a total volume of 1.667 liters, giving 0.30 (Example 1) and 0.30MAPMoVO}, A=Na (Example
molar HPMoVO. 2) or Li (Example 3) in (4-p):p volumetric ratios. The
HPMoVO is a very strong acid whose four acidic hydrogen ion concentration in each of these solutions is
hydrogens are completely dissociated from the polyoxoan 15 explicitly 0.30(4-p) mole/liter, as indicated:
ion as hydrogen ions in this solution. The hydrogen ion
concentration of this solution is explicitly 1.2 mole/liter; Example 4: 0.30M NaHa3PMoVOo: -logH = 0.00
-logH)=-0.08. Example 5: 0.30 M {NaHoPMoVOao -logH = 1.00
Example 6: 0.30 M Lios.HPMoVOao -logH = 0.00
20
Example 7: 0.30 M {LisHoaPMoVOao -logH = 1.00
Example 2 Example 8: 0.30 M {LiHPMoVOo -logH = 0.40
Preparation of 0.30M (NaPMoVO} Each of these solutions is alternatively prepared by adding
An aqueous solution of the phosphomolybdovanadate full the appropriate amount of the alkali (Na, Li) carbonate,
salt NaPMoVO was prepared according to the follow bicarbonate or hydroxide to the HPMoVO solution or
ing reaction equations: 25
to a {AHPMoVOo} solution of lesser p.
The following Example shows a method for measurement
0.5 VO+0.5 NaCO-NaVO(aq)+0.5 COf of the hydrogen ion concentration in acidic aqueous poly
oxoanion solutions and corresponding catalyst solutions,
1.5 NaCO-NaVO(aq)+11 Moo-HPO-NaPMoVO-1.5 30
which is particularly preferred for determining hydrogen ion
CO,1-3% HO concentrations in such solutions having hydrogen ion con
109.13 grams granular V2O5 (0.60 mole) was suspended centrations greater than 0.10 mole/liter. The described pro
in 1.0 liter distilled water in a Morton flask with overhead
cedures were used to determine all of the hydrogen ion
concentrations recited in the present examples and in the
stirring. The mixture was heated to ca. 60° C. and 63.59 drawings, usually expressed as -logH"). These recited
grams, granular Na,CO (0.60 mole) was slowly added in 35
hydrogen ion concentrations were measured with the indi
portions to the rapidly stirred suspension, causing CO2 cated polyoxoanions in solution in their oxidized state.
liberation and dissolution of the VOs to give an essentially
homogeneous solution. The solution was heated at reflux for Example 9
60 minutes. Approximately 1 ml of 30% HO was added
dropwise to the mixture, which was maintained at reflux for Measurement of Hydrogen Ion Concentration
an additional 60 minutes, them cooled to room temperature. -logH measurements were made with a commercial
The solution was clarified by vacuum filtration, and the glass combination pH electrode ((Orion) Ross Combination
resulting clear, orange sodium vanadate solution was then pH electrode) and commercial digital-display pH potenti
returned to a Morton flask with additional distilled water. ometer (Corning, Model 103, portable pH meter). In pH
1900.01 grams Moo (13.2 mole) was added with rapid 45 display mode, the potentiometer was calibrated to display
stirring, the mixture was heated to about 60° C., and 190.78 1.00 with the electrode in 0.30M (NaHoPMoVO}
grams granular Na,CO (1.80 mole) was slowly added in (Example 5) and 0.00 in 0.30M Nao,H.PMoVOo
portions to the rapidly stirred suspension, causing CO (Example 4), without intermediate adjustment. This calibra
liberation and dissolution of MoO 137.70 grams 85.4% tion was used to measure -logH) in 0.30M
(w/w) HPO, (1.20 mole) was then slowly added to the 50 {NaHPMo12 V.Oao solutions with p20 having
mixture, and the mixture was heated at the reflux and -logH's 1.00.
thereby converted to a clear, dark, burgundy-brown solution. To measure -log(H") in 0.30 M {NaHPMo 12
After 3 hours at reflux, the homogenous solution was cooled n)VO solutions having -logH)21.00, the potentiom
to room temperature and volumetrically diluted with dis eter was instead calibrated with the 0.30M
tilled water to a total volume of 4.0 liters, giving 0.30 molar 55 {NaHoPMoVOo solution, -logH}=1.00, and
{NaPMoVO}. 0.10 M NaHPO pH 7.0 buffer (prepared from
NaHPO.7HO and NaH2POHO in distilled water),
Example 3 taken to be -logH)=7.0. (pH 7 is far from the hydrogen ion
concentrations in the so measured polyoxoanion solutions,
Preparation of 0.30M {LiMoVO} 60 so that any discrepancy between pH and -logH") in this
The procedure was the same as for NaPMoVO4} in calibration solution only insignificantly effects the accuracy
Example 2 except that 133.00 grams granular LiCO, (1.80 of those measurements.)
mole) was substituted for the Na,CO. To measure -log(H") in 0.30M {LiHPMo12 V.
These solutions of 0.30M APMoVO, A=Na, Li, O} solutions with p>0, the corresponding Li calibration
were found to be reproducibly slightly acidic, having hydro 65 solutions were used: 0.30M LioHPMoVO, -log
gen ion concentrations -0.001M. Presumably, a minute H =0.00 (Example 6); 0.30M {LiHoPMoVO},
fraction of the Keggin polyoxoanion is hydrolytically dis -log(H=1.00 (Example 7); and 0.10M LiHPO (pre
 5,557,014
41 42
pared from HPO and LiOH in distilled water), taken to be concentration was measured to be 1.16 mole per liter;
–logH)=7. By this calibration, 0.3OM -logH =-0.07.
LiHaPMoVO (Example 8), with known -log
(H =0.40, was measured to be -logH =0.37, indicating Example 11
the accuracy of the measurement. Preparation of 0.30M NaHPMooVO}
To measure -logH in solutions having other Keggin An aqueous phosphomolybdovanadic acid partial salt
polyoxoanion concentrations, calibration solutions of solution designated 0.30M NaHPMooVOao was pre
{AHPMoVOao at the same other polyoxoanion con pared according to the following reaction equations:
centration are used: -logH) for X M
{AHPMoVOao is X(4-p). 10
Although hydrogen ion concentrations were quantita
tively measured for the polyoxoanion and catalyst solutions
in the present Examples, it is often sufficient to simply
discriminate qualitatively whether the hydrogen ion concen
tration is greater than or less than 0.10 mole/liter. A single 15 218.26 grams granular V.O. (1.20 mole) was suspended
calibration solution of {AHPMoVOao with a hydro in 2.0 liters distilled water in a Morton flask with overhead
gen ion concentration of 0.10 mole/liter can be used to stirring and the mixture was heated to about 60° C. 127.19
determine if another polyoxoanion solution has a hydrogen grams granular NaCO (1.20 mole) was slowly added in
ion concentration greater than or less than 0.10 mole/liter by portion to the rapidly stirred mixture, causing CO liberation
comparison. Preferably, the calibration solution has the same 20 and dissolution of the V2O5 to give an essentially homoge
polyoxoanion concentration and the same salt countercation neous solution. The solution was heated at the reflux for 60
as the other solution in question. Any physical measurement minutes. The solution was then lime green color due to
technique capable of discriminating between solutions hav dissolved V' which was originally present in the V.O.
ing hydrogen ion concentrations greater than or less such a Approximately 1 ml of 30% HO was added dropwise to
single calibration solution is suitable for making the com 25 the mixture causing the dark, black-bluegreen color to fade,
parison. leaving a slightly turbid, pale-tan sodium vanadate solution.
The solution was maintained at reflux for an additional 60
minutes to ensure the decomposition of excess peroxide and
Example 10 then cooled to room temperature. The solution was clarified
Preparation of 0.317M (HPMooVO4} 30 by vacuum filtration to remove the small amount (<0.1
Preparation of a desired phosphomolybdic free acid solu grams) of brown solid which contained almost all the iron
tion 0.30M {HPMoVO} by the following reaction and silica impurities originally present in the V2O5. The
equation was attempted by adapting the procedures exem clear, orange sodium vanadate solution was then returned to
plified in U.S. Pat. No. 4,156,574: a Morton flask, and 1727.28 grams MoO (12.00 mole) was
35 added with rapid overhead stirring. The mixture was heated
to about 60° C. and 137.7 grams 85.4% (w/w) HPO, (1.20
mole) was added. The mixture was heated at the reflux and
thereby convened to a clear, dark, burgundy-red solution.
545.64 grams granular V.O. (3.00 mole) and 4318.20 After 3 hours at reflux, the homogenous burgundy-red
grams MoO (30.00 mole) were suspended in 4.0 liters solution was cooled to room temperature and volumetrically
distilled water with moderate stirring. 344.23 grams 85.4% diluted with distilled water to a total volume of 4.00 liters,
(w/w) HPO, (3.00 mole) was added, the mixture was giving 0.30M (NaHPMooVO}.
diluted to a total volume of 10.0 liters with an additional 4.7 The hydrogen ion concentration of 0.30M
liters of distilled water, and the stirring mixture was heated {NaHPMoVO was measured to be 0.67 mole/liter;
to reflux. The mixture was maintained at reflux for 7 days, 45 -log(H-0.18.
after which it was cooled to room temperature, the stirring
was stopped, and the undissolved solids were allowed to fall Example 12
for five days. The burgundy-red supernatant solution was Preparation of 0.30M NaPMoVO4}
decanted from yellow residue. Repeatedly, the residue was An aqueous phosphomolybdovanadate full salt solution
suspended in water, the suspension was centrifuged, and the 50
designated 0.30M NaPMoVO})was prepared accord
supernatant was decanted. These wash supernatants were ing to the following reaction equations:
combined with the original supernatant and the resulting
solution was clarified by vacuum filtration. The volume of
the solution was reduced to about 9 liters by rotating-film
evaporation at 50° C. under vacuum. 55
The yellow residue was dried over CaCl dessicant under 1.5 NaCO+2 NaVO(aq)+10 MoO+HPO,-) Na3PMooVOoh
vacuum. The dry mass was 39.46 grams and was analyzed 1.5 CO, f--1.5 HO
to be essentially completely V.O. by quantitative elemental The procedure was the same as in Example 11 except that
analyses for P, Mo, and V. The vanadium content of the after the addition of the MoO, the mixture was heated to the
polyoxoacid solution was determined by difference. Accord 60
reflux and an additional 190.78 grams granular Na,CO.
ingly, the solution was volumetrically diluted with distilled (1.80 mole) was slowly added in portions to the stirred
water to a total volume of 9.379 liters to provide avanadium suspension, causing CO liberation, before the addition of
concentration of 0.600 gram-atoms per liter. the HPO.
The composition of this solution is designated 0.317M
{HPMooVO}+0.003M HPO. Alternatively, the 65
Examples 13-17
solution may be viewed as 0.285M HPMooV2O+
0.032M HPMoVO-0.003M HPO. Its hydrogen ion Preparations of 0.30M (NaHSPMooVOao Solutions
 5,557,014
43 44
The following polyoxoacid partial salt solutions desig allocation of sodium countercations is otherwise arbitrary,
nated 0.30M (NaHSPMooV2Oao were prepared by but this overall designation defines the elemental composi
blending 0.30M (NaH2PMoVO (Example 11) and tion of the solution. The Matveev patents' designation as
0.30M NaPMoVOao (Example 12) in (5-p):(p-2) HPMoVO) does not fully define the elemental com
volumetric ratios, and their hydrogen ion concentrations position, as it is silent on sodium and sulfate content, and is
were measured as indicated: grossly misleading, as the free polyoxoacid solution 0.30M
{HPMooVOo} (Example 10) measures -log[H]<0.
Example 13 0.30 M {NaHPMooVOo: -logH = 0.69 Example 19
Example 14 0.30M NaoHoo PMooV2Oao -logH = 0.91
Example 15 0.30 M {NaHospMoVOo -log(H) = 1.00 10
Example 16 0.30 M {NasoHoofPMooV2Oao -log(H) = 1.43 Preparation of 0.30M {NaHs PMooVOao Solution
Example 17 0.30 M (NaHoPMooVO4} -logH = 1.96 With -log(H+)=0.18 Using Sulfuric Acid
An aqueous solution comprising 0.3OM
Each of these solutions is alternatively prepared by direct {NaHPMooVOao with a hydrogen ion concentra
synthesis (see for example the preparation of 0.30M 15 tion greater than 0.10 mole/liter (-log(HK0) was prepared
LiHPMoVO in Example 22) or by adding the appro by adding 2.0 milliliter 96% (w/w) HSO (0.036 mole) to
priate amount of the sodium carbonate, bicarbonate or 100 milliliters of a solution prepared by the method of
hydroxide to a 0.30M {NaHs-PMoovOao solution of Example 18 The solution then contained 0.67M sulfate
lesser p. anions (sulfate or bisulfate), 0.30M polyoxoanion, and
20 1.80M sodium cations, and measured -logH =0.18. Since
the 0.30M (NaHPMooVO solution prepared without
Example 18 sulfuric acid (Example 11) also measures-log(H=0.18, the
present solution WaS designated 0.3OM
Preparation of 0.30M {NaHPMooVOao Solution {NaHPMooVO+0.67M NaHa SO. Again, this
With -logH")=1.00 Using Sulfuric Acid
An aqueous solution comprising 0.3OM 25 not a unique allocation of sodium countercations, but the
{NaHs PMooVOao was prepared from NaPO, overall designation defines the elemental composition of the
solution.
MoO, V.O.s, NaCO, and HSO by the method of the
Matveev patents' Example 5 (designated HPMooVO) Example 20
therein), with the following modifications: 1) a stoichiomet
ric amount of vanadium for the Keggin composition was 30 Preparation of 0.30M (NaHospMoV.O.) Solution
added, not 5% excess; 2) the solution was prepared to With Added Sodium Sulfate Salts and -logH+)=1.00
contain -logH =1.00, measured according to Example 9, To mimic the solution designated 0.30M
instead the stated "pH 1.0" since the Matveev patents give NadaHossPMooV2O4o-0.31M Natashos2SO4 pre
no indication how to calibrate or measure the stated "pH' pared by the method of the Matveev patents (Example 18),
values or how much sulfuric acid to add to obtain them; and 35 2.13 grams Na2SO (0.015 mole) and 2.21 grams
3) the amount of sulfuric acid added was measured with a NaHSOHO (0.016 mole) were dissolved in 100 milliliters
buret in order to explicitly know the complete composition of 0.30M NaHoPMooVO (Example 15). This
of the resulting aqueous polyoxoanion solutions; as follows. solution measured -logH)=0.85 instead of the expected
27.28 grams granular V2O5 (0.15 mole) and 215.91 grams 1.00. A second solution was prepared by dissolving 4.40
MoO (1.50 mole) were suspended in 0.75 liter distilled 40
grams NaSO (0.031 mole) to another 100 milliliters of
water at about 60° C. in a beaker. 37.02 grams 0.30M Naa HosaPMooVOo, and measured -logH')
NaPO-12H2O (0.15 mole) was added to the rapidly stirring =1.28. Equal volumes of the two solutions were blended to
mixture, followed by 23.85 grams granular NaCO (0.225 give a solution measuring -logH =1.00 and designated
mole), which was slowly added in portions, causing CO 0.30M NaHospMoV2O+0.31M NaHSO.
liberation. The beaker was covered with a watchglass and 45
the mixture was boiled for 90 minutes, resulting in a dark Example 21
burgundy-red solution. The watch glass was removed and
the solution was boiled uncovered an additional 90 minutes Preparation of 0.30M LiHPMooVOo
to reduce its volume to about 0.5 liter. The solution was then The procedure was the same as for 0.30M
cooled to room temperature, and its hydrogen ion concen 50 Na2HPMooVO in Example 11 except that granular
tration was measured to be -logH")=5.2.96% (w/w)HSO, LiCO was substituted for the NaCO and the preparation
was added in portions to the stirring solution to adjust its was scaled to give 10.0 liter product solution.
-logH) to 1.10, requiring 8.47 milliliters (0.153 mole). 545.64 grams granular V2O5 (3.00 mole) was suspended
The solution was then boiled uncovered for 60 minutes, in 2.0 liters distilled water in a Morton flask with overhead
cooled to room temperature, and clarified by vacuum filtra 55 stirring and the mixture was heated to about 60° C. 221.67
tion to remove a small amount of brown solid. It was then grams granular LiCO (3.00 mole) was slowly added in
volumetrically diluted with distilled water to a total volume portions to the rapidly stirred mixture, causing CO libera
of 0.500 liter. Its -logH) was readjusted to 1.00 by adding tion and dissolution of the VOs to give and essentially
0.14 milliliter 96% (w/w) HSO. homogeneous solution. The solution was heated at the reflux
The total amount of sulfuric acid added into the solution 60 for 60 minutes. The solution was then dark green due to
was 0.155 mole. Accordingly, the solution contained 0.31M dissolved V which was originally present in the VOs.
sulfate anions (sulfate or bisulfate), 0.30M polyoxoanion, Approximately 1 ml of 30% H2O, was added dropwise to
and 1.80M sodium cations. Since the 0.30M the mixture causing the dark, black-bluegreen color to fade,
NaHoPMooV2O solution prepared without sulfu leaving a slightly turbid, pale-tan sodium vanadate solution.
ric acid (Example 15) also measures -logH)=1.00, the 65 The solution was maintained at reflux for an additional 60
present solution WaS designated 0.3OM minutes to ensure the decomposition of excess peroxide and
{Na447Hos3PMooV2O4o-0.31M Nasho. SO. This then cooled to room temperature. The solution was clarified
 5,557,014
45 46
by vacuum filtration to remove the small amount (-0.1 minutes to ensure the decomposition of excess peroxide and
grams) of brown solid which contained almost all the iron then cooled to room temperature. The solution was clarified
and silica impurities originally present in the VO. The by vacuum filtration to remove the small amount (<0.2
clear, orange sodium vanadate solution was then returned to grams) of brown solid which contained almost all the iron
a Morton flask, and 4318.20 grams MoC) (30.00 mole) was and silica impurities originally present in the V2O5. The
added with rapid overhead stirring. The mixture was heated clear, orange sodium vanadate solution was then returned to
to about 60° C. and 344.24 grams 85.4% (w/w) HPO, (3.00 a Morton flask, diluted with 4.0 liters distilled water, and
mole) was added. The mixture was heated at the reflux and 3886.38 grams MoC) (27.00 moles) was added with rapid
thereby converted to a clear, dark, burgundy-red solution. overhead stirring. The mixture was heated to about 60° C.
After 3 hours at reflux, the homogenous burgundy-red 10 and 344.25 grams 85.4% (w/w) HPO, (3.00 moles) was
solution was cooled to room temperature and volumetrically added. The mixture was heated at the reflux and thereby
diluted with distilled water to a total volume of 10.00 liters, converted to a clear, dark, burgundy-red solution. After 3
giving 0.30M Na2HPMooVOo, having -logH)= hours at reflux, the homogenous solution was cooled to room
0.10. temperature and volumetrically diluted with distilled water
15 to a total volume of 10.00 liters, giving 0.30M
Example 22 {NaH2PMoVOao.
The hydrogen ion concentration of 0.30M
Preparation of 0.30M {LiHPMooVO} {NaHPMoVOao was measured to be 0.35 mole/liter;
An aqueous phosphomolybdovanadate partial salt solu -logH")=0.45
tion designated 0.30M LiHPMooVO was prepared 20
according to the following reaction equations: Example 25
VO-LiCO)2. LiVO(aq)+COf
Preparation of 0.30M LihPMoVO}
The procedure was the same as for 0.30M
1 LiCO+2 LiVO(aq)+10 Mo.OHHPO-LiHPMoVO-1 25 {NaHPMoVO in Example 24 except that 332.51
CO, i+1 HO grams granular Li2CO3 (4.50 moles) was substituted for the
Na,CO. The hydrogen ion concentration of the solution
The procedure was the same as in Example 21 except that was measured as -logH")=0.38
after the addition of the MoC), the mixture was heated to the
reflux and an additional 221.67 grams granular Li2CO (3.00 30 Example 26
mole) was slowly added in portions to the stirred suspension,
causing CO liberation, before the addition of the HPO. Preparation of 0.30M {LisHPMosVO4}
The hydrogen ion concentration was of 0.30M Preparation of an aqueous 0.30M {HPMoVO solu
{LiHPMooVO} measured to be -logH =0.63 tion from stoichiometric quantities of HPO, V.O.s, and
35 MoO in water was attempted by adapting the method
Example 23 described in U.S. Pat. No. 4,156,574, analogous to the
preparation of HaPMooVOao solution in Example
Preparation of 0.30M LiHPMooVOo 10. However, Li2CO was ultimately added to achieve
This solution was prepared by blending 0.30M complete the incorporation of the V2O5 into the polyoxoan
{LiHPMooVOo(Example 21) and 0.30M 40 ion solution, as described below. The overall equation for the
{LiHPMooVO (Example 22) in a (4-3.24):(3.24-2) synthesis became as follows:
volumetric ratio, and measured -log H--l=0.37.
Example 24 HPO 2 VO+8 MoO+ 0.575 LiCO+1425 HO->
LisH535PMosVOoh-0.575 COf
45
Preparation of 0.30M NaPMoVO} 218.26 grams granular V2O5 (1.20 mole) and 690.91
The phosphomolybdovanadic partial salt solution desig grams MoC) (4.80 mole) were suspended in 2.3 liters
nated NaH2PMoVOao was prepared according to the distilled water in a Morton flask with moderate stirring.
following reaction equations: 68.85 grams 85.4% (w/w) HPO (0.60 mole) was added,
50 the mixture was diluted to a total volume of 6.0 liters with
1.5 V2O5+1.5 Na2CO-93 NaVO(aq)+1.5 COf an additional 3.44 liters of distilled water, and the stirring
mixture was heated to reflux. The mixture was maintained at
3 NaVO(aq)+9 Mo0+HPO-Na-HPMoVOo(aq) reflux for 7 days, after which it was cooled to room
temperature, the stirring was stopped, and the undissolved
818.46grams granular V2O5 (4.50 moles) was suspended 55 solids were allowed to fall for two days. The burgundy-red
in 3.5 liters distilled water in a Morton flask with overhead supernatant solution was decanted from a yellow residue
stirring and the mixture was heated to about 60° C. 476.95 (composed principally of V2O5). Repeatedly, the residue
grams granular NaCO (4.50 moles) was slowly added in was suspended in water, the suspension was centrifuged, and
portions to the rapidly stirred mixture, causing CO libera the supernatant was decanted. These wash supernatants were
tion and dissolution of the VOs to give and essentially combined with the original and returned to the Morton flask.
homogeneous solution. The solution was heated at the reflux The VOs residue was transferred into another flask with
for 60 minutes. The solution was then dark, blue-green due about 0.5 liters distilled water and the mixture was heated to
to dissolved V' which was originally present in the V.O.s. about 60° C. 25.49 grams Li2CO chips (0.60 moles) was
Approximately 1 ml of 30% HO was added dropwise to slowly added in portions to the rapidly stirred mixture,
the mixture causing the dark, black-bluegreen color to fade, 65 causing CO liberation and dissolution of the V2O5. The
leaving a slightly turbid, pale-tan sodium vanadate solution. resulting mixture was heated at the reflux for 60 minutes,
The solution was maintained at reflux for an additional 60 giving a brown-red, slightly turbid solution. Approximately
 5,557,014
47 48
1 ml of 30% HO was added dropwise to the solution which CO1+1.5 HO
was then refluxed for an additional 60 minutes to ensure the
decomposition of excess peroxide. The orange lithium vana The procedure was the same as in Example 27 with the
date solution was cooled to room temperature, clarified by exceptions that the preparation was scaled to give 4.0 liter
vacuum filtration, and added to the original supernatant product solution (1.2 mole dissolved polyoxoanion salt) and
solution in the Morton flask. after the addition of the MoC), the mixture was heated to the
The entire solution was heated to reflux for about 3 hours, reflux and an additional 133.00 grams Li2CO chips (1.80
then cooled to room temperature. The volume of the solution mole) was slowly added in portions to the stirred suspension,
was reduced to about 1.8 liters by rotating-film evaporation before the addition of the HPO.
at 50° C. under vacuum. The homogeneous, dark burgundy O
red solution was volumetrically diluted with distilled water Examples 29-31
to a total volume of 2.0 liters, giving 0.30M
{LisHssPMosV.O., having -logH"-0. 13. Preparations of 0.30M {LiH PMosV.Oao Solutions
The following phosphomolybdovanadic acid partial salt
Example 27 15 solution was prepared by blending 0.30M
{LisHssPMosV.O. (Example 26) and 0.30M
Preparation of 0.30M {LiHPMosV.O.) {LiHPMosV.O. (Example 27) in a (4-2.5):(2.5-1.15)
The polyoxoacid partial salt solution 0.30M volumetric ratio:
{LiHPMosV.O. was prepared analogously to 0.30M
{LiHPMoVO (Example 25) and 0.30M 20 Example 29: 0.30 M {LisHPMosVOA -logH = 0.36
LiHPMooOo. (Example 21), according to the fol
lowing reaction equations:
The following 0.30M {LiH, PMosV.Oao solutions
were prepared by blending 0.30M 0.30M
2 VO+2 LiCO-4 LiVO(aq)+2 COf 25 {LiHPMosVO (Example 27) and 0.30M
4 LiVO(aq)+8 MoC)+HPO-LiHPMosVOo(aq)
{LiPMosVO (Example 28) in (7-p):(p-4) volumetric
ratios:
1091.28 grams granular V.O.s (6.00 mole) was suspended
in 2.0 liters distilled water in a Morton flask with overhead Example 30: 0.30 M LiH2PMosVOao -logH") = 0.99
stirring and the mixture was heated to about 60° C. 443.34 30 Example 31: 0.30 M LiHPMosVOo -log(H) = 1.48
grams LiCO, chips (6.00 mole) was slowly added in
portions to the rapidly stirred mixture, causing CO libera Ethylene Reactions
tion and dissolution of the V.O. to give and essentially Examples 32 through 56 show catalyst solutions within
homogeneous solution. The solution was heated at the reflux the scope of this invention and their use in processes for
for 60 minutes. The solution was then dark green due to 35 oxidation of an olefin to a carbonyl product within the scope
dissolved V which was originally present in the V2O5. of this invention, specifically exemplifying processes for
Approximately 1 ml of 30% HO was added dropwise to oxidation of ethylene to acetaldehyde. In each of these
the mixture causing the dark, black-bluegreen color to fade, examples, a palladium catalyst solution was prepared by the
leaving a slightly turbid lithium vanadate solution. The addition of the indicated palladium salt, as well as any other
solution was maintained at reflux for an additional 60 40 indicated solution components, to the indicated polyoxoan
minutes to ensure the decomposition of excess peroxide and ion oxidant solution. The hydrogen ion concentration of
then cooled to room temperature. The solution was clarified each of the exemplified catalyst solutions was the same as
by vacuum filtration to remove the small amount (-0.1 that of its parent polyoxoanion solution, as recited among
grams) of brown solid which contained almost all the iron the preceding Examples.
and silica impurities originally present in the VOs. The 45 The illustrated ethylene reactions were conducted in simi
clear, orange lithium vanadate solution was then returned to larly equipped stirred tank autoclave reactors having 300 ml
a Morton flask, and 3454.56 grams MoO (24.00 mole) was internal volume and fabricated of 316 stainless steel (Reac
added with rapid overhead stirring. The mixture was heated tor #1), Hastelloy C (Reactor #2), or titanium (Reactor #3).
to about 60° C. and 344.24 grams 85.4% (w/w) HPO, (3.00 Each autoclave was equipped with a hollow shaft stirring
mole) was added. The mixture was heated at the reflux and 50 impeller fitted with a six bladed flat disk turbine, coaxial
thereby converted to a clear, dark, burgundy-red solution. with the cylindrical internal autoclave volume. The hollow
After 3 hours at reflux, the homogenous burgundy-red shaft had a hole high in internal volume for gas inlet and
solution was cooled to room temperature and volumetrically another at the impeller turbine for efficient dispersion of the
diluted with distilled water to a total volume of 10.00 liters, gas phase through the liquid phase. The stirring impeller was
giving 0.30M LiHPMosV.O., having –logH"=0.88. 55 magnetically coupled to magnets belted to a rheostated
direct current electric motor. Each autoclave was fitted with
Example 28 a vertical baffle which extended along the internal wall
Preparation of 0.30M {LiPMosVO} through the unstirred gas-liquid interface. Resistive electric
The polyoxoanion full salt solution 0.30M heating elements were jacketed to each autoclave body and
LiPMosV.O. was prepared analogously to 0.30M
60 were controlled by a proportioning controller which moni
{LiPMo VO (Example 3), according to the following tored the liquid solution temperature via a thermocouple.
reaction equations: Volumetrically calibrated reservoirs for gas delivery were
connected to each autoclave via feed-forward pressure regu
lators.
2 VO2 LiCO-4 LiVO(aq)+2 COf 65 The ethylene reactions were conducted in fed-batch
mode, with a batch of catalyst solution and a continuous
1.5 LiCO+4 LiVOCaq)+8 MoO+HPO-LiPMooVOoh-1.5 regulated feed of ethylene from higher pressure in the
 5,557,014
49 SO
reservoir into the autoclave to maintain the set autoclave Examples 32-35
pressure. Thermocouples and pressure transducers moni
tored the temperatures and pressures of the reaction mixture Oxidation of Ethylene With 0.30M LiHPMoVO}
in the autoclave and of the ethylene in the reservoir, and a with Various Palladium Catalyst Concentrations
magnetic-sensing tachometer monitored the impeller revo In each of these examples, a palladium catalyst solution
lution rate. These transducers were all interfaced to a com was prepared by dissolving palladium(II) acetate,
puter system for continuous data acquisition as a function of Pd(CHCO), in 0.30M LiHPMoVO}(Example 22)
time. Reservoir volume, pressure, and temperature data were at the millimolar (mM) concentration indicated in Table 2.
converted to moles of ethylene in the reservoir using a 100 milliliters of each catalyst solution was reacted at 115
non-ideal gas equation incorporating the compressibility of 10 C. with ethylene at 150 psi partial pressure in Reactor #2
ethylene. using an impeller stirring rate of about 2000 RPM. The
For each exemplified ethylene reaction, 100 milliliters of reactions were allowed to proceed until ethylene consump
the indicated catalyst solution was charged to the autoclave tion ceased. In each case, the measured ethylene consump
and the gas phase in the autoclave was changed to 1 tion was close to theory (30.0 millimoles, corresponding to
atmosphere dinitrogen. The sealed autoclave was heated to 15 3000 palladium turnovers). Table 2 lists the palladium
bring the stirring solution to the indicated reaction tempera concentration, initial ethylene reaction rate, initial palladium
ture and the autogenic pressure at this temperature was turnover frequency, and total ethylene consumption of each
noted. With very gentle stirring of the solution, ethylene was reaction.
regulated into the autoclave to give a total autoclave pres
Sure equal to the autogenic pressure plus the indicated TABLE 2
ethylene partial pressure. (With only very gentle stirring of 20
the liquid phase, gas-liquid mixing is almost nil and the Pd(II)) rate Pd TF C2H4 reacted
ethylene reaction is so severely diffusion limited that no Example mM mmol 1 st s mmoles % theory
detectable reaction occurs. Gentle stirring, rather than no
stirring, was provided to avoid thermal gradients in the 32 0.045 3.2 70 27.4 91%
solution.) With the autoclave open to the forward regulated 25 33 - 0.15 1.0 74 30,6 102%
total pressure from the reservoir, the reaction was initiated 34 0.15 10.8 72 30.9 103%
35. 0.30 22.2 74 29.7 99%
by increasing the impeller stirring rate to provide efficient
dispersion of the gas through the liquid phase. The increase
in stirring rate occurred virtually instantaneously relative to FIG. 2 shows the ethylene reaction rates of Examples
the time scale of the ensuing reaction. The reaction pro 30 32-35 plotted against their palladium concentrations. The
ceeded under constant pressure while reservoir temperature initial ethylene reaction rate is linearly dependent on the
and pressure data was collected. The decrease in moles of palladium concentration; each reaction proceeded with
ethylene in the reservoir was taken to correspond to the essentially the same palladium turnover frequency. Accord
motes of ethylene reacted. ingly, the gas-liquid mixing efficiency provided these reac
For every exemplified ethylene reaction for which the 35 tions was sufficient for the ethylene oxidation rate to be
acetaldehyde product in the solution was quantitatively governed by the chemical kinetics of catalysis. These reac
analyzed (by standard gas-liquid phase chromatography tion rates were not limited by ethylene dissolution (mass
procedures), the reaction selectivity to acetaldehyde was transfer) into the catalyst solution. Each of the following
2.90%, typically 295%, and often 298%. Major by-prod exemplified ethylene reactions was likewise provided mix
ucts were acetic acid and crotonaldehyde, which are sec 40 ing which was confirmed to be sufficient for the ethylene
ondary products of acetaldehyde, by oxidation and conden oxidation rate to be governed by chemical kinetics.
sation, respectively. The amounts of these by-products
increased and the amount of acetaldehyde decreased with Example 36
the amount of time the acetaldehyde-containing catalyst
solution spent at reaction temperature and subsequently at 45 Oxidation of Ethylene with 0.30M (NaH
room temperature after the reaction of ethylene to acetalde p)PMooVO Prepared with Sulfuric Acid and Having
hyde reached completion. -log(H+)=1.00
Statistically significant modest differences in ethylene A catalyst solution was prepared containing 0.10 mM
reaction rates were measured among the three different Pd(CH-CO), dissolved in the solution designated 0.30M
reactors for otherwise nominally equivalent reactions. These 50 Na4-47Hos3PMooV2Oao-0.31 M Nashos2SO4 pre
differences were never more than 25%, usually less, and are pared according to the method of the Matveev patents as
attributed to differences in the accuracies of the temperature adapted in Example 18.
and ethylene pressure controls among the reactors. All 100 milliliters of this catalyst solution was reacted at 120°
recited comparisons of results among the following C. with ethylene at 150 psi partial pressure in Reactor #3
Examples are drawn from reactions conducted in the same 55 using an impeller stirring rate of about 2000 RPM. The
reactOr. ethylene consumption ceased within 10 minutes at 27.0
Volumetric ethylene reaction rate is reported as (millimole millimoles of ethylene, corresponding to 90% of the theo
ethylene/liter solution)/second, abbreviated mmol I s. retical vanadium(V) oxidizing capacity of the solution and
Palladium turnover frequency, TF, is reported as (moles 2700 turnovers of the palladium catalyst. The initial volu
ethylene/mole palladium)/second, abbreviated st', which is 60 metric rate of ethylene reaction was 3.0 mmol I s',
the volumetric ethylene reaction rate divided by the palla corresponding to a palladium turnover frequency of 30 s.
dium concentration. Ethylene conversion expressed as % The best exemplification in the Matveev patents (Matveev
theory refers to the % utilization of the vanadium(V) capac Example 6, see Table 1 herein), at 88 psi ethylene and 110°
ity of the solution according to reaction (12); it is 100 (moles C., provided a volumetric ethylene reaction rate of 0.670
ethylene reacted)/(moles vanadium(V)/2). The palladium 65 mmol 's', a palladium turnover frequency of 0.335 s,
turnover number, TON, is (total moles ethylene reacted/ and 150 turnovers of the palladium catalyst (40% vanadi
moles palladium). um(V) conversion). The present example provides 15 times
 5,557,014
S1 S2
greater ethylene reaction rate, 90 times greater palladium with sulfuric acid. This result confirms that the several fold
turnover frequency, and 18 times greater palladium turn greater ethylene reaction rate obtained in Example 37 as
overs. The present invention responsible for most of this compared to in Example 36 and in this Example is due to the
multiplicatively superior catalyst performance is the provi absence of sulfate ions in the catalyst solution of Example
sion of efficient mixing of the olefin with the catalyst 37.
solution in the process. Provided such mixing, the kinetic
capability of the catalyst solution in the inventive process
was revealed so unexpectedly exceptional compared to that Examples 39-43
indicated by the processes of the Matveev patents and other
background references. 10 Oxidation of Ethylene with 0.30M {NaHSPMooVOo
Solutions Having Various Hydrogen Ion Concentrations
Example 37 In each of these examples, a palladium catalyst solution
Oxidation of Ethylene with 0.3OM
was prepared by dissolving Pd(CHCO) to 0.10 mM
{Na4-47Hos3PMooV2Oao concentration in the 0.30M (NaHis-PMooV2Oao solu
A catalyst solution was prepared containing 0.10 mM 15 tion indicated in Table 3. 100 milliliters of each catalyst
Pd(CHCO) dissolved in 0.3OM solution was reacted at 120° C. with ethylene at 150 psi
NaHospMooV2Oto (Example 15). This catalyst partial pressure in Reactor #3 using an impeller stirring rate
solution is free of sulfate ions and has a hydrogen ion of about 2000 RPM, until ethylene consumption ceased.
concentration of 0.10 mole/liter (-logH)=1.00). (These are the same reaction conditions used in Examples 36
20 through 38.) In some of these examples, the reaction was
100 milliliters of this solution was reacted at 120 C. with
ethylene at 150 psi partial pressure in Reactor #3 using an repeated with 100 milliliters virgin catalyst solution using an
impeller stirring rate of about 2000 RPM. (These are the impeller stirring rate of about 3000 RPM. Table 3 lists the
same conditions as in Example 36.) The reaction consumed sodium countercation balance p and -logH") of the phos
25.0 millimoles of ethylene with an initial volumetric rate of phomolybdovanadate solution, the initial ethylene reaction
reaction of 8.2 mmol I's corresponding to a palladium rate and palladium turnover frequency, and the total ethylene
turnover frequency of 82 s. consumption.
TABLE 3
rate
{ Na its pFMoloV2O40 immol Pd TF CH reacted
Example p Example -logH) RPM s s mmoles % theory
39 2 11 0.18 2050 10.4 104 32.9 10%
300 9.7 97 31.8 106%
40 4. 13 0.69 2980 9.6 96 28.9 96%
2060 9.2 92 28.7 96%
41 440 14 0.9 2030 8.6 86 28.0 93%
3020 9. 91 27.3 919,
37 447 15 1.00 2050 8.2 82 25.1 84%
42 4.80 16 1.43 2050 48 48 25.0 83%
43 4.94 17 1.96 2050 0.7 7 23.0 77%

Comparison with Example 36 shows that the ethylene FIG. 1 shows the initial palladium turnover frequencies of
reaction rate is greater than 2.5 times faster with this catalyst 45 the examples listed in Table 3 plotted against the -logH)
solution, which is free of sulfate ions, than with the corre of their catalyst solutions. The greatest palladium catalyst
sponding catalyst solution having the same hydrogen ion activities were discovered only at hydrogen ion concentra
concentration, but prepared with sulfuric acid following the tions greater than 0.10 moles/liter (-log(H''). At the
method of the Matveev patents as adapted in Example 18. hydrogen ion concentration of 0.10 moles/liter -logH =
50 1.0), the initial palladium catalyst activity is already signifi
Example 38 cantly reduced from the higher activities achieved at greater
Oxidation of Ethylene with 0.3OM hydrogen ion concentrations, and it decreases precipitously
NaHoPMooVO Solution with Added Sodium as the concentration of hydrogen ions is decreased below
Sulfate Salts 0.10 moles/liter (-logH >1.0).
A catalyst solution was prepared containing 0.10 mM 55
Each of Examples 39, 40, and 41 shows that the measured
initial ethylene reaction rate is not significantly different
Pd(CHCO) dissolved in the solution designated 0.30M between otherwise identical reactions using impeller stirring
NaHosPMooVOo-0.31 MNaa HotSO having rates of about 2000 RPM and about 3000 RPM. This
-logH =1.00 prepared in Example 20. confirms that these reaction rates are not limited by disso
100 milliliters of this solution was reacted at 120° C. with lution (mass transfer) of ethylene into the catalyst solution,
ethylene at 150 psi partial pressure in Reactor #3 using an 60 but represent the maximal chemical kinetics capabilities of
impeller stirring rate of about 2000 RPM. (These are the these specific catalyst solutions under these specific tem
same conditions used in Examples 36 and 37.) The reaction perature and pressure conditions.
consumed 24.3 millimoles of ethylene with an initial volu The examples listed in Table 3 also show that more
metric rate of reaction of 3.1 mmol I's corresponding to effective utilization of the total vanadium(V) oxidizing
a palladium turnover frequency of 31 s. 65 capacity in the polyoxoanion solution was discovered to be
This reaction rate is essentially identical to that obtained achievable at hydrogen ion concentrations greater than 0.10
in Example 36 with the similar catalyst solution prepared moles/liter. At such increasing hydrogen ion concentrations,
 5,557,014
53 S4
the ethylene consumption vs. theory on vanadium(V) 100 milliliters of this catalyst solution was reacted at 120°
(according to reaction (12)) approached and even exceeded C. with ethylene at 150 psi partial pressure in Reactor #3
100% (suggesting partial reduction of molybdenum(VI) to using an impeller stirring rate of about 3000 RPM. (These
molybdenum(V)). At decreasing hydrogen ion concentra reaction conditions are essentially the same as for Examples
tions less than 0.10 the ethylene consumption of the solution 5 36 and 39). The ethylene reaction ceased with 21.9 milli
was significantly reduced below the theoretical capacity. moles of ethylene consumed, corresponding to reduction of
The exemplified reactions listed in Table 3 also mani 73% of the vanadium(V) oxidizing equivalents in the solu
tion. The initial volumetric reaction rate was 6.1 mmol I
fested the pronounced benefit of hydrogen ion concentra s, corresponding to a palladium turnover frequency of 61
tions greater than 0.10 moles/liter for preserving the initial s'. This result is plotted in FIG. 1.
activity of the palladium(II) catalyst. At hydrogen ion con 10 This ethylene reaction rate is about twice that of Example
centrations increasingly greater than 0.10 mole/liter, the 36, which used the corresponding polyoxoanion solution
initial ethylene reaction rate was increasingly sustained to prepared with sulfuric acid to -logH =1.0. This compari
greater ethylene conversions (and correspondingly decreas son demonstrates that the ethylene reaction rate is markedly
ing vanadium(V) concentrations). At hydrogen ion concen increased at hydrogen ion concentrations greater than 0.10
trations decreasingly less than 0.10 mole/liter, the ethylene 15
moles/liter (-logH"<1.0) even among catalyst solutions
reaction rate increasingly decelerated from the initial rate as containing sulfate ions, and even when additional sulfuric
a function of the ethylene conversion. This rate decay acid is added to achieve the greater hydrogen ion concen
ultimately led to zero rate and the increasingly less-than tration.
Stoichiometric ethylene consumptions according to reaction The ethylene reaction rate of the present Example is only
(12) measured for catalyst solutions having hydrogen ion about 60% that of Example 39, which used 0.30M
concentrations increasingly greater than 0.10 moles/liter NaH2PMooVO, the corresponding polyoxoanion
(see Table 3). solution having a comparable hydrogen ion concentration,
Improved preservation of palladium catalyst activity in but free of sulfuric acid and sulfate ions. This comparison
catalyst solutions and processes wherein the hydrogen ion demonstrates that the addition of sulfuric acid, and its
concentration is greater than 0.10 moles/liter is also evi resulting sulfate ions, depresses the ethylene reaction rate
denced in processes which repeatedly cycle the catalyst 25
even among catalyst Solutions having hydrogen ion concen
trations greater than 0.10 moles/liter.
solution between ethylene reactions and dioxygen reactions Comparison with Example 39 also shows a curtailed
(two-stage mode). At hydrogen ion concentrations increas ethylene reaction capacity, significantly below the theoreti
ingly greater than 0.10 moles/liter, the ethylene reaction rate cal vanadium(V) oxidizing capacity, for the sulfate-contain
is increasingly sustained from cycle to cycle. In contrast, at ing catalyst solution of the present Example.
hydrogen ion concentrations decreasingly less than 0.10 30 Example 46
moles/liter, the ethylene reaction rate increasingly deceler
ates from cycle to cycle until only a substantially depressed Oxidation of Ethylene with 0.30M {NaHPMoVO}
rate is sustained or the reaction effectively ceases. A catalyst solution was prepared containing 0.10 mM
Pd(CHCO) dissolved in 0.30M (NaHPMoVO
35
(Example 24), having -logH)=0.45.
Example 44 100 milliliters of this solution was reacted at 120° C. with
Oxidation of Ethylene with 0.317M (HPMooVO} ethylene at 150 psi partial pressure in Reactor #3 using an
A catalyst solution was prepared containing 0.10 mM impeller stirring rate of about 2000 RPM. The reaction
Pd(CHCO) dissolved in 0.317M {HPMooVO} consumed 42.6 millimoles of ethylene (95% of theory on
(Example 10), having-logH)=-0.07. wanadium(V)) with an initial volumetric rate of reaction of
100 milliliters of this solution was reacted at 120° C. with
40 9.4 mmol I s' corresponding to a palladium turnover
ethylene at 150 psi partial pressure in Reactor #3 using an frequency of 94 s'.
impeller stirring rate of about 2000 RPM. (The same con This reaction rate is comparable to those of Examples 39
and 40 in Table 3 for reactions of 0.30M
ditions as for the Examples in Table 3.) The reaction {NaH2PMooVO and 0.30M {NaHPMooVO in
consumed 34.1 millimoles of ethylene with an initial volu 45 the same reactor under the same reaction conditions with the
metric reaction rate of 108 mmol I's, corresponding to same palladium catalyst concentration. These
a palladium turnover frequency of 108s. The reaction was {NaHis-PMooVOao catalyst solutions have hydrogen
repeated with 100 milliliters virgin catalyst solution using an ion concentrations which bracket that of the present 0.30M
impeller stirring rate of about 3000 RPM. This reaction NaH2PMoVO catalyst solution. This comparison
consumed 33.2 millimoles of ethylene with an initial volu 50 shows that the palladium catalyst activity is not significantly
metric reaction rate of 9.4 mmol 's', corresponding to a dependent on the vanadium content of the phosphomolyb
palladium turnover frequency of 94 s. These results are dovanadate in catalyst solutions having comparable hydro
comparable to those obtained with 0.30M gen ion concentrations.
NaHPMooVO} in Example 39. Another 100 milliliters of the O3OM
This example demonstrates that phosphomolybdovanadic NaH2PMoVO palladium catalyst solution was
free acids are useful in the inventive catalyst solutions and 55
reacted with ethylene under nominally the same temperature
processes without the addition of sulfuric acid, in contrast to and pressure conditions in Reactor #2. The reaction con
the indications of the Matveev patents. sumed 45.7 millimoles of ethylene (102% of theory on
vanadium(V)) with an initial volumetric rate of reaction of
Example 45 11.6 mmol I's corresponding to a palladium turnover
60 frequency of 116 s. (Such a relative difference in measured
Oxidation of Ethylene with 0.3OM reaction rates between the indicated Reactors for nominally
{NaHis-PMooV2Oao Prepared with Sulfuric Acid to the same reaction conditions was confirmed reproducibly
with other catalyst solutions.)
A catalyst solution was prepared containing 0.10 mM Examples 47-49
Pd(CHCO2) dissolved in the solution designated 0.30M 65
{NaHPMooVO+0.67M NaHSO prepared with Oxidation of Ethylene with 0.30M {LiHPMosV.Oo}
sulfuric acid in Example 19. Solutions Having Various Hydrogen Ion Concentrations
 5,557,014
55 S6
In each of these examples, a palladium catalyst solution Example 51
was prepared by dissolving Pd(CH-CO) to 0.10 mM Oxidation of Ethylene with 0.3OM
concentration in the 0.30M {LiHyPMosV.Oao solution
indicated in Table 4. 100 milliliters of each catalyst solution (Li24H176PMooV2Oao
was reacted at 120° C. with ethylene at 150 psi partial 5 A catalyst solution was prepared containing 0.10 mM
pressure in Reactor #2 using an impeller stirring rate of Pd(CHCO) dissolved in 0.30M Li H.Mo
about 2000 RPM, until ethylene consumption ceased. Table 1oVO (Example 23), having -logH)=0.37.
4 lists the lithium countercation balance p and -logH) of 100 milliliters of this solution was reacted at 120° C. with
the phosphomolybdovanadate solution, the initial ethylene ethylene at 150 psi partial pressure in Reactor #2 using an
reaction rate and palladium turnover frequency, and the total impeller stirring rate of about 2000 RPM. The reaction
ethylene consumption. consumed 27.2 millimoles of ethylene (91% of theory on
TABLE 4
rate
{LiH(7-pPMosV.Oao Introl PdTF CH reacted
Example p Example -logH) .s s Inmoles 76 theory
47 2.5 29 0.34 1.3 113 56.6 94%.
48 4.1 30 0.99 8. 8 50.3 849,
49 4.7 31 1.48 4.1 4. 400 67%

These examples again demonstrate that greater palladium vanadium(V)) with an initial volumetric rate of reaction of
catalyst activities and greater utilization of the vanadium(V) 11.9 mmol I s' corresponding to a palladium turnover
oxidizing equivalents are provided by the inventive catalyst 25 frequency of 119s.
solutions and processes wherein the concentration of hydro Example 52
gen ions is greater than 0.10 moles/liter (-log HK1.0).
These reactions also manifested increasingly better sus Oxidation of Ethylene with 0.30M LiHPMoVO}
tained initial reaction rates to greater ethylene conversions at A catalyst solution was prepared containing 0.10 mM
hydrogen ion concentrations increasingly greater than 0.10 30 Pd(CHCO) dissolved in 0.30M LiHPMoVO}
(Example 25), having -logH)=0.38.
moles/liter.
In each of four tests, a 100 milliliter volume of this
Example 50 solution was reacted at 120° C. with ethylene at 150 psi
partial pressure in Reactor #2 using an impeller stirring rate
Oxidation of Ethylene with 0.3OM of about 2000 RPM. The individual test results are listed in
35 Table 5. The average ethylene consumption was 45.5 mil
{Li2.67H133PMoVOao
A catalyst solution was prepared containing 0.10 mM limoles (1.01% of theory on vanadium(V)). The average
Pd(CHCO) dissolved in 0.3OM initial volumetric rate of reaction was 11.6 mmol I's
{LiHPMoVO (Example 8), having -logH = corresponding to a palladium turnover frequency of 116 s.
0.37. Table 5 collects results from preceding Examples for
100 milliliters of this solution was reacted at 120° C. with 40 reactions of ethylene with various 0.30M
ethylene at 150 psi partial pressure in Reactor #2 using an AH3PMoc12-VO4o
impeller stirring rate of about 2000 RPM. The reaction bapalladium catalyst solutions having comparable hydro
consumed 22.0 millimoles of ethylene. This is 147% of gen ion concentrations, all conducted in Reactor #2 under
theory on the vanadium(V) oxidizing equivalents and indi the same reaction conditions.

TABLE 5
late
tAH3 in-pMoc12-nVOao: IIIol PdTF CHA reacted
Example A p -logH) 1. S s mmoles 76 theory
50 Li 2.67 0.37 12.4 24 22.0 147
51 Li 3.24 2 0.37 11.9 119 27.2 91
52 Li 3 3 0.38 18 18 46.1 O2
1.3 13 44.9 100
11.9 19 46.1 02
1.4 14 45.0 100
47 Li 2.5 4 0.36 11.3 113 56.6 94
46 Na 3 3 0.45 1.6 16 45.7 02

60
The reactions listed in Table 5 exhibited comparable
initial ethylene reaction rates, indicating that the palla
cates significant reduction of the molybdenum(VI) in the dium(II) catalyst activity is not significantly dependent on
the average vanadium content, n, of the phosphomolybdo
PMoV, Olof anion as well. The initial volumetric rate of 65 vanadate anions or on the vanadium(V) concentration
reaction of 12.4 mmol 's' corresponding to a palladium among these catalyst solutions having comparable hydrogen
turnover frequency of 124 s. ion concentrations. These rate measurements spanned solu
 5,557,014
57 58
tions having vanadium(V) concentrations from 0.30 g-at 100 milliliters of this solution was reacted at 115° C. with
oms/liter to 1.2g-atoms/liter at constant polyoxoanion con ethylene at 150 psi partial pressure in Reactor #3 using an
centration. These rate measurements spanned solutions impeller stirring rate of about 2000 RPM. The reaction
having average vanadium contents from n=1, which con consumed 40.5 millimoles of ethylene (90% of theory on
tains substantially only the PMoVOao anion, to n-4, vanadium(V)) with an initial volumetric rate of reaction of
which contains a distribution of H.PMoV.O." 8.7 mmol I's corresponding to a palladium turnover
anions including substantial concentrations of anions with frequency of 87 s.
x>4. These results indicate that the phosphomolybdovana
date anions do not coordinate palladium(II) under the reac Example 54
tion conditions, as the different phosphomolybdovanadates 10
do not give different palladium catalyst activity. Oxidation of Ethylene with 0.30M NaHPMoVO}
Palladium(II) catalytic activity independent of vanadi with Added Sodium Sulfate Salts
um(V) concentration was also evidenced in exemplified A sulfate-containing stock solution was prepared by dis
reactions provided hydrogen ion concentrations greater than solving NaSO to 1.5M concentration in a volume of the
0.10 mole/liter by their ethylene reaction rate over the course 15 catalyst solution of Example 53. Another was prepared by
of the reaction, which did not decelerate in proportion to the dissolving NaHSOHO to 1.5M concentration in another
decreasing vanadium(V) concentration. volume of the same catalyst. These two stock solutions were
As these ethylene reaction rates are dependent on the blended in a 7:3 ratio to obtain a catalyst solution with the
palladium(II) concentration and substantially independent of same -logH) measurement as the parent catalyst solution
the vanadium(V) concentration and specific phosphomolyb 20 of Example 53. This solution is designated 0.30M
dovanadate identity, the superior olefin oxidation reactivity {NaHPMoVO4}+1.5M NaHoaSO containing 0.10
provided by hydrogen ion concentrations greater than 0.10 mM NaPdCl4.
mole/liter in the inventive catalyst solutions and processes is 100 milliliters of this solution was reacted with ethylene
attributed to a favorable influence of such hydrogen ion under the same conditions used in Example 53. The ethylene
concentrations on the palladium(II) activity for olefin oxi 25 reaction ceased with 33.0 millimoles of ethylene consumed
dation according to reaction (14). Accordingly, a capability (73% of theory on vanadium(V)). The initial volumetric rate
for superior palladium catalyst activity may be provided in of reaction was 3.1 mmol I's corresponding to a palla
a solution of any polyoxoanion comprising vanadium(V) dium turnover frequency of 31 s'.
wherein the concentration of hydrogen ions is greater than Comparison with Example 53 shows that the presence of
0.10 mole/liter (provided, of course, that the constitution and 30 the sulfate ions in the present Example results in a reaction
efficacy of the specific vanadium(V) oxidant is not detri rate less than 40% of that obtained in their absence. The
mentally affected by such hydrogen ion concentration). present Example also shows a curtailed ethylene reaction
In such acidic aqueous solution in the absence of coor capacity, significantly below the theoretical vanadium(V)
dinating ligands or anions, palladium(II) is thought to exist oxidizing capacity, for this sulfate-containing catalyst solu
as tetraaquopalladium(II), Pd(H2O).”. The precipitously 35 tion.
decreasing ethylene reaction rate for catalyst solutions at
decreasing hydrogen ion concentrations of 0.10 mole/liter Example 55
and less (-logH)2-1) may be attributed to the double Oxidation of Ethylene with 0.30M {NaHPMoOo. with
deprotonation of Pd(H2O), with pK's about 2, to less 25 mM Chloride
active hydroxo species according to reaction (16). The 40
The procedure was the same as for Example 53 with the
lograte vs. -logH) slope between the reactions of exception that 2.46 millimole NaCl was added in the 100
Examples 42 and 43, with -logH) at 1.43 and 1.96 milliliters of catalyst solution which was reacted with eth
respectively, is -1.5, consistent with the removal of more ylene. The chloride concentration of this solution was 25
than one proton from the active palladium catalyst. mM.
The superior olefin oxidation reactivity in the inventive 45
The reaction consumed 43.7 millimoles of ethylene (97%
catalyst solutions and processes essentially free of sulfuric of theory on vanadium(V)) with an initial volumetric rate of
acid and sulfate ions must likewise be attributed to a reaction of 3.4 mmol I S. corresponding to a palladium
favorable influence of omitting sulfuric acid and sulfate ions turnover frequency of 34s.
on the palladium(II)-olefin reaction. Palladium(II) is known
not to coordinate sulfate ions in water, so it is doubtful that 50
Example 56
sulfate directly influences the palladium(II) catalyst. More
likely, sulfate salts decrease ("salt out”) the solubility of the Oxidation of Ethylene With 0.30M NaHPMoVO}
olefin in the aqueous solution and thereby decrease the with 25 mM Chloride and Added Sodium Sulfate Salts
concentration of dissolved olefin available for reaction with The procedure was the same as for Example 54 with the
palladium(II). Accordingly, superior olefin oxidation rates 55 exception that 2.46 millimole NaCl was added in the 100
may be expected for any aqueous catalyst solution essen milliliters of sulfate-containing catalyst solution which was
tially free of sulfuric acid and sulfate ions. Accordingly, a reacted with ethylene. The solution contained 25 mM chlo
capability for superior olefin oxidation rates may be pro ride and 1.5M sulfate ions, having the same -logH) as the
vided in any polyoxoanion solution which is essentially free catalyst solution of Example 55.
of sulfuric acid and sulfate ions. 60 The ethylene reaction ceased with 33.2 millimoles of
Example 53 ethylene consumed (74% of theory on vanadium(V)). The
initial volumetric rate of reaction was 1.8 mmol I s
Oxidation of Ethylene with 0.30M NaHPMoVOo corresponding to a palladium turnover frequency of 18s.
A catalyst solution was prepared containing 0.10 mM Comparison with Example 55 again shows that the pres
NaPdCl dissolved in 0.30M (NaH2PMooVOo 65 ence of the sulfate ions decreases the ethylene reaction rate,
(Example 24), having-log(H=0.45 and 0.40 mM chloride in this case to about 50% of that obtained in the absence of
1O.S. sulfate. The present Example also again shows curtailed
 5,557,014
59 60
ethylene reaction capacity, significantly below the theoreti
cal vanadium(V) oxidizing capacity, in the presence of
Sulfate.
Butene Reaction
The following example shows a catalyst solution within 5 This is analogous to the oxidation of olefins to carbonyl
the scope of this invention used in a process for the oxidation compounds, illustrated in reaction (12) for the oxidation of
ethylene to acetaldehyde. Carbon dioxide is readily removed
of 1-butene to 2-butanone within the scope of this invention. from the catalyst solution prior to the dioxygen reaction. The
The 1-butene reaction was conducted in a 300 ml Hastelloy use of carbon monoxide as reductant preceding dioxygen
C stirred tank autoclave reactor equipped similarly to the 10 reactions, instead of an olefin, facilitated the measurement
previously described reactors used for the preceding volumetric dioxygen reaction rates and dioxygen reaction
examples of ethylene reactions. The volumetrically cali capacities characteristic of the vanadium(IV)-polyoxoanion
brated 1-butene reservoir and its feed lines to the reactor
solutions under the specific reaction conditions, as it avoids
were heated to keep the contained 1-butene in the gas state. any potential confounding influences of olefin oxidation
The reaction was conducted in fed-batch mode by the 15 products on the data without the inconvenience of com
methods described for the ethylene reactions. pletely removing them from the aqueous solutions prior to
the dioxygen reaction. Multiple cycles of carbon monoxide
Example 57 and dioxygen reactions could also be conducted with a
single batch of catalyst without inconvenient removal of
Oxidation of 1-butene with 0.30M {LiHPMoVO} 20 olefin oxidation products.
A catalyst solution was prepared containing 0.60 mM To reduce a catalyst solution with carbon monoxide in the
Pd(CHCO) and 30 mM LiCl dissolved in 0.30M autoclave, the gas phase over the solution in the sealed
{LiHPMoVO (Example 25), having -logH)=0.38. autoclave was first changed to 1 atmosphere dinitrogen. The
150 milliliters of this catalyst solution was reacted at 130° stirring solution was then heated to the desired reaction
C. with 1-butene at 200 psi partial pressure using an impeller 25 temperature, typically 120° C. Carbon monoxide was regu
stirring rate of about 2000 RPM. The initial volumetric rate lated into the autoclave, to give a total autoclave pressure of
of 1-butene reaction was 5.9 mmol 's', corresponding to at least 150 psig, typically 250 psig. The catalyst solution
was reduced by increasing the impeller stirring speed suf
a palladium turnover frequency of 10 s. The stirring was ficiently to provide efficient dispersion of the gas through the
stopped 60 seconds after its initiation to stop the reaction. 26 30 liquid phase for at least 10 minutes. The reaction solution
millimoles of i-butene were consumed within that time, was then cooled to room temperature, the autoclave gas
corresponding to 39% utilization of the vanadium(V) oxi pressure was vented, and the gas phase in the autoclave was
dizing capacity of the solution. The predominant product of replaced with atmosphere dinitrogen. This involved sev
this 1-butene reaction is 2-butanone. eral cycles of dispersing dinitrogen under pressure through
Dioxygen Reactions 35 the liquid phase and venting to 1 atmosphere to remove
Examples 58 through 67 show processes within the scope essentially all dissolved carbon dioxide.
of this invention for oxidation of vanadium(IV) and for When reduced in this way with excess carbon monoxide,
regeneration of a polyoxoanion oxidant comprising vana the catalyst solution become fully reduced. That is, all the
dium by reaction of an aqueous solution of vanadium(IV) vanadium(V) is reduced to vanadium(IV). Fractionally
and a polyoxoanion with dioxygen. 40 reduced catalyst solutions were prepared by fully reducing
The illustrated dioxygen reactions were conducted in the the corresponding volume fraction of the solution with
same autoclave reactors used for the preceding Examples of excess carbon monoxide, following which the remaining
ethylene reactions. The autoclave reactors were equipped as volume fraction of oxidized solution was deaerated and
previously described, with the exception, when indicated, added into the autoclave under dinitrogen.
that the single vertical baffle was replaced with a cage of 45 For each exemplified dioxygen reaction, with 100 milli
liters of the indicated reduced solution in the sealed auto
four vertical baffles, at 90° relative positions around the clave under 1 atmosphere dinitrogen, the autoclave was
cylindrical internal autoclave wall, to provide more turbu heated to bring the stirring reduced solution to the indicated
lent gas-liquid mixing at a set impeller stirring speed. The reaction temperature and the autogenic pressure at this
dioxygen reactions were conducted in fed-batch mode with 50 temperature was noted. With very gentle stirring of the
a batch of reduced vanadium-polyoxoanion solution and a solution, dioxygen was regulated into the autoclave to give
continuous forward regulated feed of dioxygen from higher a total autoclave pressure equal to the autogenic pressure
pressure in a volumetrically calibrated reservoir into the plus the indicated dioxygen partial pressure. (With only very
autoclave. Reactions were monitored and data acquired over gentle stirring of the liquid phase, gas-liquid mixing is
time as previously described for the ethylene reactions. 55 almost nil and the dioxygen reaction is so severely diffusion
Reservoir volume, pressure, and temperature data were limited that no detectable reaction occurs. Gentle stirring,
converted to mole of dioxygen in the reservoir using the rather than no stirring, was provided to avoid thermal
ideal gas equation. gradients in the solution.) With the autoclave open to the
For each exemplified dioxygen reaction, the indicated forward regulated pressure from the reservoir, the reaction
vanadium-polyoxoanion solution was charged to the auto 60 was initiated by increasing the impeller stirring speed to
clave and the vanadium(V) was reduced to vanadium(IV) in provide efficient dispersion of the gas through the liquid
the autoclave prior to the reaction with dioxygen. Except phase. The increase in stirring rate occurred virtually instan
when otherwise indicated, the vanadium-polyoxoanion solu taneously relative to the time scale of the ensuing reaction.
tion included a palladium(II) catalyst and was reduced by The reaction proceeded under constant pressure while res
reaction with carbon monoxide. Palladium catalyzes the 65 ervoir temperature and pressure data was collected. The
oxidation of carbon monoxide to carbon dioxide by the decrease in moles of dioxygen in the reservoir was taken to
vanadium(V), according to the following equation: correspond to the moles of dioxygen reacted.
 5,557,014
61 62
Example 58 gen partial pressure was nominally 36 psi. Table 8 lists the
Oxidation of Reduced 0.30M LiHPMooV.O. With impeller stirring rate, initial dioxygen reaction rate, and total
Dioxygen at Various Gas-Liquid Mixing Efficiencies dioxygen consumption for the individual dioxygen reac
tions. These dioxygen reaction rates are plotted against the
100 milliliters of a catalyst solution containing 0.15 mM impeller stirring speed in FIG. 3.
Pd(CHCO) dissolved in 0.30M {LiHPMooVOo
(Example 22), having-logH)=0.63, was charged to Reac TABLE 8
tor #2 equipped with a single vertical baffle and alternately rate O, reacted
fully reduced with carbon monoxide and reacted at 120° C.
with dioxygen at 27 psi partial pressure at the impeller 10 RPM mmol l st mmoles % theory
stirring rates indicated in Table 6. The dioxygen reactions
were allowed to proceed until dioxygen consumption 1130
2050
1.7
5.4
23.6
245
105
111
ceased. For each reaction, the measured dioxygen consump 3050 10.0 23.3 104
tion was close to theory for complete oxidation of the
vanadium content of the solution, 100% as vanadium(IV), 15
according to reaction (13): 15.0 millimoles dioxygen to FIG. 3 plots the initial dioxygen reaction rates of
oxidized 60 mg-atoms vanadium(IV). Table 6 lists the Examples 58, 59, and 60 against impeller stirring speed. The
impeller stirring rate, initial dioxygen reaction rate, and total reaction rates in each Example are linearly dependent on the
dioxygen consumption for the individual reactions. These stirring rate up to the highest stirring rates available in the
dioxygen reaction rates are plotted against the impeller reactors. Accordingly, these initial dioxygen reaction rates
stirring speed in FIG. 3. 20 are limited by the rate of dioxygen dissolution (mass trans
fer)into the vanadium(V)-polyoxoanion solution, which
TABLE 6
increases as the gas-liquid mixing efficiency in the reactor is
improved by increased stirring speed. Differences in reac
Iate O, reacted tion rates among these three Examples manifest differences
25 in baffling and impeller efficiency among the reactors which
RPM mmoll's mmoles % theory influence the gas-liquid mixing efficiency obtained as a
1020 0.4 15.0 100
function of the impeller stirring rate.
1640 2.4 14.8 99 Additionally, these reactions proceed at near constant
1960 3.7 15. 101 rate-the rate does not decelerate in proportion to the
2630 5.8 14.2 95
30
decreasing vanadium(IV) concentration-up to high con
3280 7.8 14.5 97 version of the vanadium(IV) to vanadium(V), usually>80%
conversion, typically to ~90% conversion. The intrinsic
kinetic reactivity of these concentrated vanadium(IV) solu
Example 59 tions at these temperatures under these conditions exceeds
the rate at which dioxygen can be dissolved into solution,
Oxidation of Reduced 0.30M NaHPMoVO. With 35 until the vanadium(IV) concentration is substantially
Dioxygen at Various Gas-Liquid Mixing Efficiencies depleted by the reaction.
100 milliliters of a catalyst solution containing 0.10 mM The results from Examples 58, 59, and 60 each indicate,
NaPdCl and 4.60 mM. NaCl dissolved in 0.30M by back-extrapolation that significant reaction rates could be
{NaHPMoV Oao (Example 24), having-log(H")=0.45, obtained only at any stirring rates greater than about 800
was charged to Reactor #2 equipped with a cage of four 40 RPM in these reactors. This threshold is taken to indicate the
vertical baffles and alternately fully reduced with carbon lowest stirring rate at which gas could be successfully
monoxide and reacted at 110° C. with dioxygen at 25 psi suctioned down the hollow impeller shaft as far as the
partial pressure at the impeller stirring rates indicated in impeller for efficient dispersion through the liquid phase.
Table 7. The dioxygen reactions were allowed to proceed The best exemplification in the Matveev patents (Matveev
until dioxygen consumption ceased. Table 7 lists the impel 45 Example 6, see Table 1 herein) provided a volumetric
ler stirring rate, initial dioxygen reaction rate, and total dioxygen reaction rate of 0.335 mmol I's at 110° C. with
dioxygen consumption for the individual dioxygen reac 51 psi dioxygen with a solution said to have "pH... adjusted
tions. These dioxygen reaction rates are plotted against the to 1.0” by HSO during its preparation in oxidized form.
impeller stirring speed in FIG. 3. This rate just approaches the slowest dioxygen reaction rate
TABLE 7
50 measured in the preceding examples at lower pressure.
(Gas-liquid mass transfer limited reaction rates are directly
rate O, reacted dependent on the pressure of the reacting gas and little
RPM mmol is Immoles % theory
affected by temperature.) The highest reaction rates achieved
in the preceding examples is over 40 times greater than this
1230 2.6 not available 55 best exemplification in the Matveev patents, again with
1480 4.5 24.9 111 lower pressure. The present invention most responsible for
2030
2050
9.4
9.8
25.8
23.2
115
103
this multiplicatively superior reaction performance is the
2810 140 not available
provision of efficient mixing of the dioxygen with the
reduced vanadium-polyoxoanion solution in the process.
60 Provided such mixing, the reactivity of the vanadium(IV)-
Example 60 polyoxoanion solution in the inventive process was revealed
so unexpectedly exceptional compared to that indicated by
Oxidation of Reduced 0.30M (NaHPMoVOo with the processes of the Matveev patents and other background
Dioxygen at Various Gas-Liquid Mixing Efficiencies references. Even greater dioxygen reaction rates can be
The procedure was the same as in Example 59 with the 65 obtained in even more efficient gas-liquid mixing reactors.
exception that the reactions were conducted in Reactor #3 The Matveev patents state that the "pH" of their solutions
equipped with a cage of four vertical baffles and the dioxy is preferably at 1.0 and, "At lower pH values, the rate of the
 5,557,014
63 64
oxygen reaction is appreciably diminished.” Similarly, LiHPMooVOo is not significantly different from that
Koordinatsionnaya Khimiya, vol. 3, (1977), pp. 51-58 of reduced 0.30M {LiHPMooVOao under these condi
(English translation edition pp.39-44 shows a graph with a tions. The gas-liquid mixing efficiency for these exemplified
maximum rate of only 0.57 mmol I's at about "pH' 3 reaction is not sufficient to reveal any differences in the
which declines to almost negligible rate by "pH' 1. Attri chemical kinetic reactivity of the two solutions with dioxy
butions of diminished rates to lower "pH' values obligato gen which might be attributed to their different hydrogen ion
rily implies that the diminished rates are limited by the concentrations. This Example also demonstrates that the
chemical kinetics of the reaction. (Rates which are limited present invention provides dioxygen reaction rates in vana
by the chemical kinetics cannot be increased by increased dium(IV)-polyoxoanion solutions having hydrogen ion con
gas-liquid mixing efficiency.) In contrast to this teaching, 10 centrations at least as great as 0.8 mole per liter when
and as demonstrated in the preceding and following essentially all the vanadium(IV) is oxidized to vanadium(V)
Examples, the present invention provides processes for which are multiplicatively superior to the rates disclosed in
oxidizing vanadium(IV) in polyoxoanion solutions, even the background references for solutions said to have "pH' 1
solutions having -logHK1.0, at rates multiplicatively and greater when oxidized.
Only with solutions having still greater hydrogen ion
faster than the processes disclosed reported in the Matveev 15 concentration than that in the present Example were dimin
patents for solutions said to have "pH 1.0". ished chemical kinetic reactivities with dioxygen revealed
under the reaction conditions of the present Example. For
Example 61 example, under these conditions, fully reduced 0.317M
Oxidation of Reduced 0.30M LiHPMoVO} with HPMooVO (Example 10), having -log(HF
Dioxygen 20 0.07 when oxidized, initially reacts with dioxygen at the
The procedure of Example 58 was used for reactions of essentially constant mass-transfer limited rate to about
40-60% conversion of the vanadium(IV) to vanadium(V),
fully reduced 0.30M {LiHPMoVO} at 120° C. with after which chemical kinetics limited rates were revealed,
dioxygen at 281 psi partial pressure in Reactori2 equipped with the rate decelerating with greater than first-order depen
with a single vertical baffle using impeller stirring rates of 25 dence on the remaining vanadium(IV) concentration. (The
2000+100 RPM. Three separate 100 milliliter solution fraction of vanadium(IV) converted at the mass-transfer
samples were each reduced and reacted with dioxygen two limited rate will decrease with increased mass-transfer rate
times. Between the tests on the separate solution samples, provided by more efficient gas-liquid mixing.) Even this
the reactor was disassembled, cleaned, and reassembled solution, having -logHKO when oxidized, can provide
several times for other experiments. Reactor disassembly 30 reaction rates with dioxygen for conversion of a substantial
and reassembly was found to be a source of variability in the fraction of the vanadium(IV) to vanadium(V) which exceed
mass-transfer limited reaction rates as are variations in
dioxygen partial pressure and impeller stirring speed. The the rates disclosed in the background references for solu
tions said to have "pH' 1 and greater,
average initial dioxygen reaction rate for the six reactions
was 3.2 mmol I's with a standard deviation of 0.5 mmol 35
Example 63
I s. For each reaction, the measured dioxygen consump Oxidation of Reduced Palladium-Free 0.3OM
tion was close to theory for complete oxidation of the {LiHPMoVO} with Dioxygen
wanadium content of the solution, 100% as vanadium(IV), 100 milliliter of 0.30M {LiHPMoVO (Example
and the reactions proceeded at near constant rate (the rate did 22) was charged to Reactor #2 equipped with a single
not decelerate in proportion to the decreasing vanadium(IV) 40 vertical baffle and the gas phase in the autoclave was
concentration) up to >80% conversion of the vanadium(IV) changed to 1 atmosphere dinitrogen. 0.81 milliliters hydra
to vanadium(V). zine hydrate (14.25 millinoles hydrazine) was injected into
Example 62 the solution and the solution was heated to 120° C. with
gentle stirring. Dinitrogen evolution from hydrazine oxida
Oxidation of Reduced 0.30M {LiHPMooVO} with 45 tion was monitored by pressure increase, up to constant
Dioxygen pressure. With very gentle stirring of the solution, dioxygen
A catalyst solution was prepared containing 0.15 mM was regulated into the autoclave to add 29 psi to the total
Pd(CHCO), dissolved in 0.30M LiHPMooVOo autoclave pressure. The dioxygen reaction was then initiated
(Example 21) and having -logH =0.10 (0.8 mole per liter using an impeller stirring rate of 2000 RPM as previously
hydrogen ion concentration). Two separate 100 milliliter 50 described. 12.9 millinole of dioxygen was consumed, cor
solution samples were each reduced and reacted with dioxy responding to 91% of the hydrazine reducing equivalents
gen two times in Reactor #2 under the same nominal added to the solution. The initial dioxygen reaction rate was
reaction conditions as in Example 61. The tests on the 2.7 mmol I's and the reaction proceeded at near constant
separate solution samples were interspersed with the those rate (the rate did not decelerate in proportion to the decreas
of Example 61 and other experiments, with intervening 55 ing vanadium(IV) concentration) up to ~90% of the total
reactor disassembly and reassembly. The average initial oxygen consumption.
dioxygen reaction rate for the four reactions was 2.5 mmol This reaction rate is not significantly different from that of
I's with a standard deviation of 0.5 mmol I s. For Example 61, in which a palladium salt was added in the
each reaction, the measured dioxygen consumption was 0.30M LiHPMoVO solution to catalyze the reduc
close to theory for complete oxidation of the vanadium 60 tion of vanadium by carbon monoxide. This demonstrates
content of the solution, 100% as vanadium(IV), and the that palladium is not required in the process of the present
reactions proceeded at near constant rate (the rate did not invention for the oxidation of vanadium(IV) to vanadi
decelerate in proportion to the decreasing vanadium(IV) um(V).
concentration) up to >80% conversion of the vanadium(IV) Example 64
to vanadium(V). 65
Comparison with Example 61 shows that the measured Oxidation of Reduced 0.30M {LiHPMoVO} with
rate of dioxygen reaction for reduced 0.30M Dioxygen
 5,557,014
65 66
100 milliliters of a catalyst solution containing 0.10 mM (Except for the addition of the dissolved sulfate salts, this
Pd(CHCO) dissolved in 0.30M LiHPMosV.O. solution has the same composition as the solution used in
(Example 31), having-logH =1.48, was charged to Reac Example 66.) The solution was alternately fully reduced
tor #2 equipped with a cage of four vertical baffles, fully with carbon monoxide and reacted with dioxygen under the
reduced with carbon monoxide, and reacted at 120° C. with same conditions used in Example 66. Two cycles of reduc
dioxygen at 30 psi partial pressure using an impeller stirring tion and dioxygen reaction gave the reaction rates and
rate of 2000 RPM. Dioxygen consumption ceased at 27.8 dioxygen consumptions listed in Table 9.
millimoles, corresponding to 93% of the vanadium(IV) Comparison with Example 66 shows that the presence of
capacity of the solution, assuming 100% of vanadium was the sulfate ions in the present Example results in a reaction
rate less than 50% of that obtained in their absence.
initially reduced to vanadium(IV). The dioxygen reaction 10
rate was initially 5.4 mmol I s' and the reaction pro TABLE 9
ceeded at near constant rate (the rate did not decelerate in
proportion to the decreasing vanadium(IV) concentration) sulfate rate O reacted
up to ~80% of the total oxygen consumption. Example molelliter mmol is mmoles % theory
15
Example 65 66 ZO 3.3 26.2 117
3.2 28.3 126
Oxidation of Reduced 0.30M LisHPMoVO} with 67 1.5 1.5 23.4 104
Dioxygen 1.6 22.6 100
Following the reaction of Example 64, Reactor #2 was 20
drained, rinsed with water, tided by heating, and charged Gas-liquid diffusion limited reaction rates are positively
with 100 milliliters of a catalyst solution containing 0.10 dependent on the solubility of the gas in the liquid. The
mM Pd(CHCO) dissolved in 0.30M {LisHPMosV. decrease in diffusion limited rates of dioxygen reaction
O} (Example 29), having-logH =0.36, all without any caused by the addition of sulfate salts is reasonably attrib
disassembly of the reactor. The solution was fully reduced 25 utable to a decrease in the solubility of dioxygen in the
with carbon monoxide and reacted with dioxygen under the aqueous solution. Chemical kinetic rates for reaction of
same conditions used in Example 64. Dioxygen consump dissolved oxygen depend on the concentration of dissolved
tion ceased at 29.1 millimoles, corresponding to 97% of the oxygen, and so also depend on dioxygen solubility. Accord
vanadium(IV) capacity of the solution, assuming 100% of ingly, a capability for increased dioxygen reaction rates,
vanadium was initially reduced to vanadium(IV). The 30
whether diffusion limited or chemical kinetics limited, may
dioxygen reaction rate was initially 6.4 mmol I's and the be provided in any vanadium(IV)-polyoxoanion solution
reaction proceeded at near constant rate (the rate did not which is essentially free of sulfuric acid and sulfate ions.
decelerate in proportion to the decreasing vanadium(IV) With the benefit of the present invention, the teaching of
concentration) up to ~80% of the total oxygen consumption. the Matveev patents and other background references that
Comparison with Example 64 shows that a diffusion 35
rates of dioxygen reaction are appreciably diminished at
limited dioxygen reaction rate of a reduced 0.30M {LiH,- decreasing "pH values may now be understood to reflect
p)PMosVO solution having a hydrogen ion concentra the increasing amounts of sulfuric acid added to decrease
tion substantially greater than 0.10 mole per liter when "pH'. That is, their diminished rate results not simply from
oxidized is not diminished relative to that of one having a the decreased "pH', but in part or in whole from the
hydrogen ion concentration substantially less than 0.10 mole increased sulfate concentration.
40
per liter when oxidized. The present inventions have been shown by both descrip
tion and exemplification. The exemplification is only exem
Example 66 plification and cannot be construed to limit the scope of the
invention. Persons of ordinary skill in the art will envision
Oxidation of Reduced 0.30M {NaHPMoVO} with 45
equivalents to the inventive solutions and processes
Dioxygen described by the following claims which are within the
100 milliliters of a catalyst solution containing 0.10 mM scope and spirit of the claimed invention.
NaPdCl and 25.0 mM NaCl dissolved in 0.30M We claim as our invention:
NaHPMoVOao (Example 24), having-logH)=0.45, 1. In an aqueous catalyst Solution for the oxidation of an
was charged to Reactor #3 equipped with a cage of four 50
olefin to a carbonyl product comprising a palladium catalyst,
vertical baffles and alternately fully reduced with carbon a polyoxoanion oxidant comprising vanadium, and hydro
monoxide and reacted at 110° C. with dioxygen at 36 psi gen ions, the improvement comprising providing a concen
partial pressure at an impeller stirring rate of 2000 RPM tration of said hydrogen ions greater than 0.10 mole per liter
until the dioxygen consumption ceased. Two cycles of of solution when essentially all the oxidant is in its oxidized
reduction and dioxygen reaction gave the reaction rates and 55
state, and providing said solution essentially free of sulfuric
dioxygen consumptions listed in Table 9. acid and sulfate ions.
2. The solution of claim 1 wherein said polyoxoanion
Example 67 oxidant further comprises phosphorus and molybdenum.
3. The solution of claim 2 wherein said polyoxoanion
Oxidation of Reduced 0.30M NaHPMoVO Con oxidant comprises a phosphomolybdovanadate having the
taining Added Sodium Sulfate Salts with Dioxygen 60 formula
Following the reaction of Example 66, Reactor #3 was
drained, rinsed with water, dried by heating, and charged
with 100 milliliters of a catalyst solution containing 0.10 (HPMota V.O.or
mM NaPdCl and 25.0 mM NaCl dissolved in the solution
designated 0.3OM {NaHPMoVO+1.5M 65 wherein 0<x<12 and 0sy<(3+x), or mixtures thereof.
NaHSO prepared as in Example 54 and having -log 4. The solution of claim 1 further comprising at least one
H=0.45, all without any disassembly of the reactor. of an olefin and a corresponding carbonyl product.
 5,557,014
67 68
5. In a Wacker process for the manufacture of acetalde 11. The process of claim 7 wherein the olefin is propylene
hyde by oxidation of ethylene using an aqueous catalyst and the carbonyl product is acetone.
solution, the improvement wherein the aqueous catalyst 12. The process of claim 7 wherein the olefin is one of
solution is the solution of claim 1. 1-butene, cis-2-butene, and trans-2-butene, or mixtures
6. A process for oxidation of an olefin to a carbonyl thereof, and the carbonyl product is 2-butanone.
product comprising:
contacting the olefin with an aqueous catalyst Solution,
13. The process of claim 7 wherein the olefin is one of
3-methyl-1-butene and 2-methyl-2-butene, or mixtures
wherein the aqueous catalyst solution is the solution of thereof, and the carbonyl product is 3-methyl-2-butanone.
claim .
7. In a process for oxidation of an olefin to a carbonyl 10 14. The process of claim 7 wherein the olefin is 4-methyl
product comprising 1-pentene and the carbonyl product is 4-methyl-2-pen
tanOne.
reacting the olefin with an aqueous catalyst solution
comprising a palladium catalyst, a polyoxoanion oxi 15. The process of claim 7 wherein the olefin is cyclo
dant comprising vanadium, and hydrogen ions, the pentene and the carbonyl product is cyclopentanone.
15
improvement comprising providing a concentration of 16. The process of claim 7 wherein the olefin is cyclo
said hydrogen ions greater than 0.10 mole per liter of hexene and the carbonyl product is cyclohexanone.
solution when essentially all the oxidant is in its 17. The process of claim 7 further comprising contacting
oxidized state, and providing said aqueous catalyst dioxygen with the aqueous catalyst solution.
solution essentially free of sulfuric acid and sulfate 20
18.The process of claim 7 further comprising the steps of
OS removing the carbonyl product from the aqueous solution,
8. The process of claim 7 wherein said polyoxoanion contacting dioxygen with the aqueous catalyst solution at
oxidant further comprises phosphorus and molybdenum. conditions sufficient to regenerate the oxidant in its oxidized
9. The process of claim 8 wherein said polyoxoanion state, and contacting additional olefin with the aqueous
oxidant comprises a phosphomolybdovanadate having the 25 catalyst solution.
formula
19. In an aqueous catalyst solution for the oxidation of an
olefin to a carbonyl product comprising a palladium catalyst,
a polyoxoanion oxidant comprising vanadium, and hydro
gen ions, the improvement comprising providing said solu
wherein 0<x<12 and 0sy<(3+x), or mixtures thereof. 30 tion essentially free of sulfuric acid and sulfate ions.
10. The process of claim 7 wherein the olefin is ethylene
and the carbonyl product is acetaldehyde. ck k k