PRODUCTION OF 20 TONN PER DAY OF CUMENE BY BENZENE

AND PROPYLENE

Session 2015-19

Supervised By
Dr. K.S Baig
Ms. Ammara Waheed

Group Members
Muhammad Aqib UW-15-Ch.E-BSc-040
Talha Ishaq UW-15-Ch.E-BSc-008
Muhammad Zaid UW-15-Ch.E-BSc-028
Hafiz Faisal Naveed UW-15-Ch.E-BSc-021

Department Of Chemical Engineering

Wah Engineering College,
University of Wah, Wah Cantt

i
 Table of Contents
CHAPTER # 01........................................................................................................................1

1 INTRODUCTION............................................................................................................1

1.1 CUMENE....................................................................................................................2

1.1.1 Structure...............................................................................................................2

1.1.2 Preferred IUPAC name........................................................................................2

1.1.3 Background..........................................................................................................3

1.1.4 Occurrence...........................................................................................................3

1.2 PHYSICAL PROPERTIES AND THERMODYNAMIC DATA:.............................4

1.3 REACTIONS OF CUMENE.......................................................................................5

1.3.1 Cumene into Phenol and Acetone........................................................................5

1.4 INDUSTRIAL APPLICATIONS................................................................................5

1.4.1 Importance of Cumene.........................................................................................5

1.4.2 Phenol and acetone production............................................................................5

1.4.3 Bisphenol A (BPA) production............................................................................6

1.4.4 Cumene hydroperoxide Production......................................................................6

1.5 HANDLING, SAFETY AND STORAGE..................................................................6

1.5.1 Storage..................................................................................................................6

1.5.2 Handling...............................................................................................................6

1.5.3 Safety....................................................................................................................7

1.6 SHIPPING...................................................................................................................7

1.7 MOTIVATION............................................................................................................8

1.8 FEASIBILITY.............................................................................................................8

1.9 CUMENE MARKET TREND....................................................................................8

1.10 CUMENE PRODUCTION AND CONSUMPTION IN WORLD.............................9

1.11 CUMENE PRODUCTION AND CONSUMPTION IN PAKISTAN......................10

1.12 FUTURE TREND.....................................................................................................10

ii
CHAPTER # 02......................................................................................................................11

2 MANUFACTURING PROCESSES.............................................................................11

2.1 CUMENE PRODUCTION METHODS...................................................................12

2.1.1 Cumene production by using solid phosphoric acid catalyst.............................12

2.1.2 Cumene production by using Aluminum Chloride Catalyst..............................15

2.1.3 CD cumene process by using zeolite as a catalyst.............................................17

2.2 COMPARATIVE STUDY OF PRODUCTION METHODS...................................18

2.3 PROCESS SELECTION...........................................................................................19

2.3.1 CD-cumene process...........................................................................................19

2.4 PROCESS FLOW DIAGRAM.................................................................................22

2.5 RAW MATERIAL....................................................................................................22

2.5.1 Benzene..............................................................................................................23

2.5.2 Propylene............................................................................................................23

2.6 CAPACITY SELECTION........................................................................................23

Bibliography...........................................................................................................................25

iii
 List of Tables
Table 1-Physical properties [4]..................................................................................................4
Table 2-Thermodynamic properties...........................................................................................4
Table 3-Comparative study......................................................................................................18
Table 4-Kinetics of alkylation and trans alkylation reactions [18]..........................................20
Table 5-Pakistan phenol consumption according to imports value [22]..................................23

iv
 List of Figures
Figure 1-Reaction of cumene.....................................................................................................5
Figure 2-Prodution of phenol and acetone from cumene...........................................................8
Figure 3-Cumene global market.................................................................................................9
Figure 4-World cumene consumption in 2017...........................................................................9
Figure 5-Consumption of phenol in future...............................................................................10
Figure 6-Cumene production by using solid phosphoric acid catalyst [11].............................14
Figure 7-Cumene production by using Aluminum Chloride Catalyst [14]..............................16
Figure 8-CD cumene process by using zeolite as a catalyst [16].............................................17
Figure 9-Prodution of cumene by zeolite catalyst....................................................................22
Figure 10-Phenol consumption in Pakistan..............................................................................24

v
Chapter 01 Introduction

CHAPTER # 01
1 INTRODUCTION

1
Chapter 01 Introduction

1.1 CUMENE
Isopropyl benzene is commonly called as Cumene, its chemical formula is (C 9H12). It is
flammable hence catches fire and also colorless liquid. It has a penetrating gasoline-like odor.
Its boiling point is 152°C. It is a pure liquid at surrounding conditions. Propylene and
Benzene are raw material to produce high concentration cumene. Aliphatic substitution is
done on aromatic hydrocarbon hence it is an organic compound. Crude oil and refined fuels
are composed of Cumene. Cumene hydroperoxide is further produced from cumene that is
manufactured as a pure substance on an industrial scale that is an intermediate substance
because in the further production of other important industrial chemicals, chiefly phenol and
acetone. Cumene is an aromatic compound consists of a benzene ring. High content cumene
is produced from propylene (C3H6) and benzene (C6H6). Manufacturing of cumene from the
older techniques has become outdated based on the use of phosphoric acid (H 3PO4) and
aluminum chloride (AlCl3) as a catalyst because of the advancement and the successful
commercialization of the zeolite‐based technology. Chiefly all cumene produced worldwide
is consumed for the production of phenol and acetone. So, resulting requirement for cumene
is bound to the phenol market.[CITATION Wik13 \l 1033 ]

1.1.1 Structure

1.1.2 Preferred IUPAC name

(Propan-2-yl) benzene
Other names
Isopropyl benzene
Cumene
Cumol
(1-Methylethyl) benzene [ CITATION Hen13 \l 1033 ]

2
Chapter 01 Introduction

1.1.3 Background
Cumene (isopropyl benzene) is manufactured by reaction of propylene (C 3H6) with benzene
(C6H6). The synthesis of cumene was first described in 1841 by Gerhardt and Cahours when
it is produced by distilling lime with cumic acid. Alkylation of benzene with Aluminum
Chloride that is used as a catalyst to manufacture cumene was well-defined by
Radziewanowski in 1892. Before the improvement of the cumene to synthesize phenol and
acetone, cumene had been used widely during World War II, it was used to increase octane
number for piston-engine aircraft fuel. Now, mostly cumene is a raw material for the
production of phenol (C6H5OH) globally, a process that synchronously manufactures most of
the supply of acetone (C3H6O) globally. Typically, cumene is produced at the same facility
that manufactures phenol and acetone.
Transportation of Benzene and propylene feeds are done through tanker trucks and is stored
in tanks as liquids.

1.1.4 Occurrence
Natural occurrence
Cumene is a natural constituent of crude oil and it occurs by nature in plants, marsh grasses
and foodstuff. Composition of cumene in crude oil is 0.1% weight but it may consist of
cumene up to 1% weight. Petrol contains cumene range from 0.14 to 0.51% volume, with an
average of 0.3% vol. Premium diesel fuel contains 0.86% weight of cumene.[CITATION
Int121 \l 1033 ]
Environmental Occurrence
Cumene is discharged into the environment during its production, use and transmission. As it
is present in crude oil and finished fuels so it is a major source of pollution; cumene is
liberated as a result of incomplete combustion of fossil fuels from vehicles, oils spills,
transmission and distribution of fossils fuels, and evaporation from gasoline stations. It also
get released as it is used a solvent during manufacture of paint and vulcanization of rubber
but is very minor, and also from tobacco smoke.

3
Chapter 01 Introduction

1.2 PHYSICAL PROPERTIES AND THERMODYNAMIC DATA:

Table 1-Physical properties [CITATION Int12 \l 1033 ]

Physical Properties Values

Color Colorless
Odor Gasoline like
Boiling Point 152 °C at 760 mmHg
Melting Point -96 °C
Flash Point 31°C
Solubility 50 mg/L at 25 °C
Density 0.862 g cm−3 at 20 ᵒC
Vapor Density 4.1 (Air = 1)
Vapor Pressure 8 mmHg
Stability Volatile
Auto Ignition 420 °C
Viscosity 0.85 mm²/s at 25 °C

Table 2-Thermodynamic properties

Properties Value

Critical Pressure 3220 kPa

Critical Temperature 351.4 °C

Critical Density 0.280 g cm−3

Heat of Vaporization at Boiling Point 312 J/g

Heat of Vaporization at 25ᵒC 367 J/g

Heat of Formation at 25ᵒC -44,150 J/mol

Free Energy at 25ᵒC 137,000 J/mol

Heat Capacity (liquid) at 25ᵒC 197 J/(mol.K)

Heat Capacity (ideal vapor) at 25ᵒC 153 J/(mol.K)

Threshold Limit Value 50 ppmv

4
Chapter 01 Introduction

1.3 REACTIONS OF CUMENE

1.3.1 Cumene into Phenol and Acetone

The air oxidation of cumene also known as isopropyl benzene at high pressure and at a
temperature of 100-130ᵒC give rise to the production cumene hydro-peroxide which when
reacted with dilute Sulphuric acid both phenol and acetone are obtained.

Figure 1-Reaction of cumene

1.4 INDUSTRIAL APPLICATIONS

1.4.1 Importance of Cumene

Cumene is expended mainly (95%) as an intermediate in the manufacturing of phenol and
acetone. Other uses are as the production of styrene, α-methyl-styrene, acetophenone,
detergents and di-isopropyl-benzene; it is used as a solvent for fat and resins; and in printing
and production of rubber. Small amounts are used in blending of gasoline and as it is also a
constituent of high-octane aviation fuel because its octane rating is high.[CITATION DeW07
\l 1033 ]

1.4.2 Phenol and acetone production

Phenol is aromatic organic compound having an appearance of white crystalline volatile
solid.It is slightly acidic. It is slightly soluble in mineral oil.
It is used as headache medicine and one of highly explosive, picric acid.
Its resins are used to make plastics and thermosetting plastics.
About 98% of cumene is used to produce phenol (C6H5OH) and its co-product acetone
(C3H6O). However, the prophecy for cumene largely depend on on the performance
of phenol’s derivatives which have developed in well growth rates for cumene.

5
Chapter 01 Introduction

1.4.3 Bisphenol A (BPA) production

One of the main causes of enhancing demand of cumene is that due to growing production of
bisphenol A (BPA), a product of phenol and acetone. Bisphenol-A is the largest phenol
derivative (BPA) which provides the increasing polycarbonate (PC) sector. PC resins are
good alternative in place of glass and metals in automotive. Glazing and sheet uses, such as
architectural, security and glazing outlets, are also important PC applications. Other use for
Polycarbonate (PC) is used in optical media such as compact discs (CDs) and digital versatile
discs (DVDs). Polycarbonate (PC) and epoxy resins are the main drivers of BPA demand.

1.4.4 Cumene hydroperoxide Production 

Cumene hydroperoxide is an organic hydroperoxide, it is an intermediate in
the cumene process for the manufacturing of phenol and acetone from benzene and propene.
It is generally used as an oxidizing agent means it gains electron.
The main drivers in the acetone market are methyl methacrylate (MMA) and Bisphenol A
(BPA). Nearly all Methacrylate (MMA) is used to synthesize homopolymers and copolymers
with electronic applications such as flat screen TVs and liquid crystal displays (LCDs)
providing growth chances.

1.5 HANDLING, SAFETY AND STORAGE

1.5.1 Storage
Cumene is stable, but when it reacts with air it may form peroxides so for this purpose tests
are done for the presence of peroxides before heating or purifying. The chemical is also
catches fire and so unsuitable with strong oxidizing agents. Gas chromatography–mass
spectrometry (GCMS) instruments are used for the test of peroxides in environmental
laboratories.

1.5.2 Handling
For the safe storage the container is firmly closed in a dry and well-airy place. Containers
which are already opened must be carefully resealed and kept still to avoid escape. It is
stored under non-reactive gas.
From contact with skin and eyes it must be avoided. Inhalation of vapor or mist should be
avoiding. Must be kept away from the causes of ignition – Smoking must be avoided. Take
measures to avoid the buildup of electrostatic charge.

6
Chapter 01 Introduction

1.5.3 Safety
Respiratory protection
Where hazard estimate shows air-purifying respirators are suitable, use a full-face respirator
with multi-purpose combination respirator casings as a backup to engineering controls. If the
respirator is the only means of protection, full-face supplied air respirator should be used. Use
respirators and components verified and permitted under suitable government standards.
Hand protection
Gloves must be used while handling it. Gloves must be inspected before their use, they must
be first inspected. Suitable proper glove removal technique must be followed when skin
contact with this product. After use of contaminated gloves eradicate them after use in
correspondence with valid laws and good laboratory practices. Hands must be wash and dry
them.
Eye protection
Face shield and safety glasses must be used. Equipment that are approved for eye protection
tested and approved under suitable government standards must be used.
Skin and body protection
Chemicals and flame retardant antistatic protective clothing must be use. The type of
protective equipment must be selected according to the concentration and amount of the
dangerous substance at the specific workplace.
Hygiene measures
Handle in accordance with good industrial hygiene and safety practice. Wash hands before
breaks and at the end of workday.

1.6 SHIPPING
Cumene is transported mainly through trucks and barge. Marathon Petroleum Corporation
(MPC) transports cumene through the freight ship and truck to the Midwest and the U.S. Gulf
Coast customers.
Barge is a long flat-bottomed boat to carry shipment on canals and rivers, its own power is
manage for shipping or can be pulled by another.[CITATION 20118 \l 1033 ]

7
Chapter 01 Introduction

1.7 MOTIVATION
About 98% of Cumene Obtained is used to manufacture Phenol. Pakistan imports all of its
demands of Phenol from China Netherland and other countries and a lot of foreign exchange
is added in the import bill. The main purpose of our project is to produce cumene which will
be used in the manufacturing of phenol whose demand is increasing in Pakistan of about 6-
7% yearly which provides us the suitable chances to earn profit and save valuable foreign
exchange

1.8 FEASIBILITY
In Pakistan the raw material for the manufacture of Cumene is Benzene and propylene and all
of it is imported from China. CPEC provides us the chance to obtain the raw material
economically and Byco is also establishing its plant in Hub Baluchistan which will
manufacture our raw material and thus our raw material can be obtained from the required
resources. The plant is also feasible because of the fact the byproduct of this process is di-iso
propyl benzene which is recycled back for the production of cumene. The environmental
hazards are also minimum because of less waste disposal and limited releases of off gases
thus provides us the basis for establishing this plant.

1.9 CUMENE MARKET TREND

The Global Cumene market was worth $15,466.1 million in 2012, and is estimated to reach
$24,129.02 million by 2018, at a CAGR of 6.7%. World Cumene Market is increasing due to
increasing of demand for phenol in several industries such as composites, plastics, laminates
and other industries. Phenol largest application and accounted for 61.4% of the total market
in 2016.[CITATION Gra17 \l 1033 ]

Figure 2-Prodution of phenol and acetone from cumene

8
Chapter 01 Introduction

Asia was the biggest market and contributed for 47.8% of the overall market in 2016. Its
growth is increasing the automotive industry and construction, especially in countries such as
China, Japan, and India.

Figure 3-Cumene global market

1.10 CUMENE PRODUCTION AND CONSUMPTION IN WORLD

Assessed that about 12,400.4 KT of cumene was internationally expended in 2012, and
demand is likely to increase the consumption about 16,997.9 KT by 2018, at an assessed
CAGR (Compound annual growth rate) of about 5.1%. Biggest consuming market of cumene
is Northeast Asia (47% in 2017).
Total world cumene consumption is increase at an average rate of almost 3% per year by
2022. [CITATION Che18 \l 1033 ]

9
Chapter 01 Introduction

Figure 4-World cumene consumption in 2017

1.11 CUMENE PRODUCTION AND CONSUMPTION IN PAKISTAN

Pakistan has no cumene production plant. It is mainly used for the production of phenol and
Pakistan is importing Phenol that is the major product of cumene. Benzene and Propylene are
raw materials for the production of cumene. Pakistan first aromatic plant for the production
of benzene is under construction in Hub, Baluchistan. It has a capacity of 1,00,000 tons per
year of benzene. Also, benzene and propylene can be imported from China through China
Pakistan Economic Corridor (CPEC).
Cumene is not being consumed but has 3845 metric ton per year of phenol consumption, and
cumene is raw material for phenol production.

1.12 FUTURE TREND

All of the phenol is being imported and there is no plant for the production of cumene. Plant
for the production of cumene is of great importance because it will lessen our import of
phenol and we can produce phenol and cumene in our country. We don’t have to be
dependent on other countries phenol production. It will enhance the market of Pakistan. In the
future, we will produce a sufficient amount of cumene for further production of phenol.

10
Chapter 01 Introduction

7000

6000

5000
Consumption

4000

3000

2000

1000

0
2005 2010 2015 2020 2025 2030
Years

Figure 5-Consumption of phenol in future

CHAPTER # 02
2 MANUFACTURING PROCESSES

11
Chapter 01 Introduction

2.1 CUMENE PRODUCTION METHODS

Cumene is pure chemical intermediate produced by the Friedel-crafts reaction process which
use acidic catalyst for alkylate benzene with propylene. Generally cumene is synthesized
commercially by three process.[CITATION Wil04 \l 1033 ]
1. Alkylation using Phosphoric acid.
2. Alkylation using Aluminium chloride.
3. CD-Cumene process.

2.1.1 Cumene production by using solid phosphoric acid catalyst

Introduction
Solid phosphoric acid is a feasible catalyst for the manufacture of cumene. In last few years,
producers have been given increasing encouragements for improved cumene product which is
used for the production of phenol and acetone.
Process description
Propylene and benzene are the raw materials required for the synthesis of cumene. Raw
material is in the storage tanks having a capacity of 500 MT and centrifugal pumps are used
to pump raw material to the unit. Benzene stream and the benzene that is pumped by the
vaporizer along 25 atm pressure and vaporizer temperature at 243oC, and mixed with the
propylene at identical temperature and pressure as that of benzene stream. Then mixture of
reactant is passed through a fired superheater having a reaction temperature of 350 oC. After
that the mixture of reactant is put into the up-flow reactor, which work at pressure 3-4 MPa
and at temperature of 200-260°C. The solid phosphoric acid catalyst offers chiefly complete
conversion of propylene on a single-pass basis. The individual reactor effluent maximum
yield consists of 94.8 Weight. % cumene and 3.1 Weight. % of (DIPB). The remaining 2.1 %
are heavy aromatics. This high production of cumene is grew without trans alkylation of
(DIPB) and it is alike to the solid phosphoric acid catalyst process. [CITATION jie13 \l
1033 ]
The cumene produce by using this method is almost 99.9 Weight. % pure and the heavy
aromatics with octane number of 109, can be used as high-octane Petroleum (gasoline)

12
Chapter 01 Introduction

blending components or combined with additional benzene and sent to the second trans-
alkylation reactor of the plant where di-isopropyl benzene is further converted into cumene to
enhance the overall product of plant. The overall yields of cumene for this process is 97-98
Wight. % with the use of trans alkylation reactor and 94-96 Weight. % without trans
alkylation reactor. The reactions for cumene production from benzene and propylene are as
follows:

Main Reaction:                     
    C3H6    +     C6H6        →    C6H5-C3H7
   Propylene   Benzene          Cumene
By-Product Reaction           
  C3H6      +  C6H5-C3H7   →        C12H18
Propylene    Cumene               Di iso propyl benzene (DIPB)
Advantages
 The SPA catalyst gives the complete conversion of propylene on single pass basis.
 Cumene produce by this method is 99.9 Wt. % pure.
 The removal of byproduct is relatively simple.

Disadvantages

 Cumene production is limited to 95% because of the oligomerization of propylene and

formation of heavy alkylate by-products.
 The process requires a relatively high benzene propylene molar feed ratio 7:1 in order
to maintain cumene yield.
 The catalyst cannot be generated and must be dump at the end of each short catalyst
cycle.

13
Chapter 01 Introduction

14
Chapter 01 Introduction

Figure 6-Cumene production by using solid phosphoric acid catalyst [CITATION

Sho12 \l 1033 ]

2.1.2 Cumene production by using Aluminum Chloride Catalyst

Introduction
Aluminum chloride is a favored alkylating agent for the production of cumene. Basically, the
design is same to that defined for other processes, having pretreatment section if required, a

15
Chapter 01 Introduction

reactor and distillation section. The reaction operating conditions, with arrangement for the
feeding catalyst and recycle of PAB for dealkylation are however quite different.
Process description
Aluminum chloride is a group of Friedel-Crafts type catalyst used for addition of alkyl group
to the aromatic ring of benzene. The chemical reaction takes place at 3.4 to 3.5 atm pressure
and 130-135 C temperature. Reaction is exothermic is heat is evolved during reaction. Feed is
o

heated in the preheater with the reactor effluent and even it is used for steam production. Two
reactors are used to carry out the trans alkylation and alkylation process. Benzene and
propylene are mixed and vaporized in a vaporizer. Feed stream is heated to get reactor
condition along with catalyst. Benzene and propylene are converted in alkylation reactor to
obtain cumene and DIPB. The effluent stream is mixed with recycle stream of poly propyl
benzenes and fed into trans alkylation reactor where it reacts with excess benzene and
converts into cumene.[CITATION Sam13 \l 1033 ]
Catalyst is separated from the organic compounds by washing with water in separator. For
removal of traces of acid, separated organic mixture is treated with caustic. Then catalyst is
concentrated with steam and recycled backed to the alkylation reactor. By using series
of distillation towers cumene is distilled and unreacted raw material is separated..
Advantages
 Propane in propylene feed is removed as liquid petroleum gas
 By product removal is quite simple
 Poly alkyl benzene can be recycled back to reactor as aluminum chloride catalyst has
ability to trans alkylate PAB in presence of benzene.

Disadvantages
 Feed pretreatment is required.
 High corrosion
 Environmental hazard
 Washing step for catalyst removal[CITATION Sam \l 1033 ]

16
Chapter 01 Introduction

Figure 7-Cumene production by using Aluminum Chloride Catalyst [ CITATION Sam18

\l 1033 ]

17
Chapter 01 Introduction

2.1.3 CD cumene process by using zeolite as a catalyst

Introduction
The CD- Cumene process produces excessive high purity cumene using zeolite catalyst
which is non-corrosive in nature and environmentally friendly.
Process description
Cumene is produced by the catalytic alkylation of benzene and propylene. CD-cumene
process uses a zeolite catalyst for production of cumene. Zeolite catalyst is non-corrosive in
nature and environmentally friendly. This modern technology has higher product yields, with
lower capital investment, than the other outdated acid- based processes.
The single catalytic distillation column combines reaction and fractionation in a single unit
operation. Alkylation reaction takes place at low temperature and isothermally. By distillation
Reaction products are removed continuously from the reaction region. Due to continuously
removing product from reaction zone the formation of by-product impurities is limited and
increase the product quality and yields. Lower operating temperatures result in lower
equipment size and low operating pressures, which support to decrease capital investment,
and operation safety is improved. All waste heat, including the heat of reaction, is recovered
and utilized for improved energy efficiency.[ CITATION Jie13 \l 1033 ]

Figure 8-CD cumene process by using zeolite as a catalyst [CITATION Ham14 \l 1033 ]

18
Chapter 01 Introduction

2.2 COMPARATIVE STUDY OF PRODUCTION METHODS

Table 3-Comparative study

Methods Solid phosphoric acid Aluminum chloride Zeolite Catalyst

Feedstock Propylene and benzene Propylene and Propylene and

benzene benzene
Mole ratio 7:1 2-3:1 4:1

Reactor Fixed bed Reactor Homogeneous liquid- Adiabatic fixed bed

phase reactor reactor
Pressure 3-4 MPa 3.4-3.5 atm 2.5 - 3.5 MPa
Temperature 200-260 oC 130-135 oC 150-200 oC
Selectivity 94-96 % 99% 99.98 %
By product Di iso propyl benzene Poly alkyl benzene Di-isopropyl benzene

Reason to use R2 Increase overall yield Increase overall yield Increase overall yield

State of the Art Well known technology Well known technology Mostly used technology
Advantages Complete conversion Poly alkyl benzene High product purities,
of propylene, Cumene may be recycled to the Ability to regenerate
product 99.9 wt.% pure reactor as aluminum the catalyst,
chloride has ability to Eliminates the waste
trans alkylated PAB in disposal problem,
presence of benzene. Non-Corrosive
Disadvantages Cumene yield is limited Feed pretreatment is No disadvantages of
to 95%, molar feed required, the presence this process because of
ratio 7:1 of benzene of HCL in and around maximum conversion
propylene, Catalyst is can cause trouble. 99.97 % and there is
not regeneratable and High Corrosion, ability to regenerate
disposed at the end of Environmental the catalyst
each short catalyst Hazards, washing step
cycle. for catalyst removal.

2.3 PROCESS SELECTION

So that we are selecting CD-cumene process of manufacturing of cumene.
 Extends reactor run length over one year without regeneration, sustain high
conversion and selectivity.
 Decrease capital investment, improves safety and operability.
 Reduces utilities and operating costs, recovers all waste heat and heat of reaction.

19
Chapter 01 Introduction

 Improves economics-plans can be custom designed to process specific feedstocks

including less expensive feedstock.
 Maximum conversion
 Corrosion free process
 catalyst is regenerated, and trans alkylation reactions also occur over this catalyst in
second reactor

So, we are selecting CD cumene process for production of cumene which use zeolite as a
catalyst.

2.3.1 CD-cumene process

Introduction
The CD- Cumene process synthesize high pure cumene by using zeolite catalyst which is
non-corrosive in nature and ecologically friendly. The alkylation reaction is done in fixed-
bed reactors at temperatures below than other acid catalyst-based processes.
Process description
Alkylation of benzene with propylene is use to produce cumene in presence of zeolite-based
catalysts. To keep the reactants in the liquid phase throughout the reactor the reactions are
carried out in liquid phase at temperature range which gives complete conversion of
propylene. To use liquid-phase reactors consider a series of two reactors. The first reactor is
known as the alkylation reactor, the following reactions take place

C 3 H 6 +C 6 H 6 k 1 C9 H 12
→

Propylene Benzene Cumene

C 3 H 6 +C 9 H 12 k 2 C 9 H 12
→

Propylene Cumene DIPB

The first reaction produces the main product of the process. The produced cumene further
react with propylene to produce di-iso- propyl-benzene or higher propyl-benzenes. For
simplicity, it was expected that the only by-product is DIPB. The reaction rate constants are
listed below in Table
The reactor is an adiabatic fixed bed of catalyst pellets with the inlet temperature range of
150 ℃to 200 ℃. The pressure is kept high enough to ensure that the boiling temperature of
the solution is at least 20℃ higher than the temperature anywhere else in the reactor.
Therefore, the pressure is kept between 2.5 and 3.5 MPa conditional on the composition of

20
Chapter 01 Introduction

the mixture and the temperature of the reactor. The benzene to propylene mole ratio (B/P) is
kept at more than 4 in the reactor.[CITATION Ham141 \l 1033 ]
An excess amount of benzene is essential in the reactor for the following reasons:
 To absorb heat produced by exothermic reactions in the reactor.
 To boost the selectivity of the cumene reaction over the DIPB reaction.
 To overwhelm the reaction between propylene molecules, which produces higher
linear hydrocarbons.

The boiling temperature of these hydrocarbons is close to that of benzene, thus, separating
them from benzene (to avoid accumulation) becomes problematic.

Table 4-Kinetics of alkylation and trans alkylation reactions [ CITATION Bah14 \l

1033 ]
Reactor Reaction Rate Expression Rate Constants
Alkylation Cumene reaction k 1Cp −52564
k 1=6510 exp ⁡( )
RT
DIPB reaction k 2Cp −55000
k 2=450 exp ⁡( )
RT
Trans alkylation Forward k 3 xB xD −100000
k 1=2.529 x 108 exp( )
RT
Backward k 4 X 2c k 4=3877 x 109 exp(
−122240
)
RT

In the second adiabatic reactor, known as the trans alkylation reactor, the produced DIPB is
transformed back to cumene in a reaction with benzene in the liquid phase:
C 6 H 6 +C 12 H 18 ⇆ 2C 9 H 12
Benzene DIPB Cumene

The inlet temperature for this reactor is about 220℃ – 240℃, and the benzene to DIPB mole
ratio is between 5 and 10. The reaction rate constants of these reactions are listed in Table
Use of the second reactor improves the overall yield of the alkylation process and hence the
profitability of the whole plant.
A typical process flow diagram of cumene production using a zeolite catalyst is shown
below. Fresh and pure benzene is introduced in the vessel V-1, mixed with the recycled
benzene coming from the separation section, and pumped to 3.6 MPa. The recycled benzene
is use to maintain the benzene to propylene mole ratio. The refinery-grade propylene is

21
Chapter 01 Introduction

pumped to 3.6 MPa and mixed with the benzene stream. The mixed feed stream is preheated
to 170℃ using the outlet product hot stream of the alkylation reactor in the heat exchanger
E-1. The earlier mentioned reactions are carried out in the alkylation reactor R-1. Both
reactions are extremely exothermic, thus, the temperature of the reactants increases
progressively along the reactor length. The inlet temperature and B/P must be sustained in
such a way that no vapor is produced in the reactor. 100% conversion of propylene is desired
due to two significant facts: first, the unreacted propylene would escape from the process in
the propane column (C-1) with propane, which is economically unfavorable; second, benzene
and propylene are reacted with a 1:1mole ratio and the inlet flow rate of benzene to the
process should be reduced in the fresh benzene stream, which in turn decreases the overall
production of the plant.
The reactor run-off is passed through the heat exchangers E-1 & E-2 and is fed to the propane
column in which propane is totally removed from additional components. The condenser E-3
is partial and its pressure is 1.5 MPa. The top stream of the column has fuel value and can be
used in the fuel cycle of the process. The bottom stream leaving the propane column is mixed
with the product stream of trans alkylation reactor R-2 (trans effluents) and is fed to the
benzene column C-2 in which benzene is collected from the top stream and sent back to both
reactors. In this column, the concentration of benzene in the bottom stream must be tiny to
guarantee high purity of cumene in the next column. Bottom streams of the benzene column
are sent to the cumene column C-3 where cumene product is obtained as top product with at
least 99.5% purity. The bottom stream of this column, mostly contain DIPB, is fed to the
trans alkylation reactor R-2. In this reactor, DIPB is transformed to cumene. The reactor run-
off is then sent to the benzene column C-2. The minimum and optimum reflux ratio and
number of trays columns were calculated according to the following techniques.[ CITATION
Bah141 \l 1033 ]

2.4 PROCESS FLOW DIAGRAM

22
Chapter 01 Introduction

Figure 9-Prodution of cumene by zeolite catalyst

2.5 RAW MATERIAL

Our raw material is benzene and propylene which used for production of cumene. Pakistan
organic industry stayed silent due to deficiency of elementary chemicals such as ethylene,
propylene, butylene and BTX including (Benzene, toluene, xylene). In Pakistan the raw
material of manufacture of Cumene is Benzene and propylene and all of it is imported from
China. CPEC provides us the chance to obtain the raw material economically and Byco
Petroleum Pakistan Limited (BPPL) is also launching its plant in Hub Baluchistan which will
produce our raw material and thus our raw material can be obtained from the required
resources.

2.5.1 Benzene
Benzene is natural component of crude oil .It is a colorless and highly flammable liquid with
a sweet smell, and is accountable for the aroma nearby petrol stations. It is used in the
synthesis of chemicals such as ethyl benzene and cumene, of which billions of kilograms are
produced annually.[CITATION wik18 \l 1033 ]

23
Chapter 01 Introduction

2.5.2 Propylene
Propene is a byproduct of oil refinery and natural gas processing. During refining of
oil, ethylene, propene, and other compound created as a result of cracking larger
hydrocarbons. A main source of propene is naphtha cracking.[CITATION CAM13 \l 1033 ]

2.6 CAPACITY SELECTION

Pakistan do not import cumene because 98% cumene is used for the production of phenol so,
Pakistan import phenol from globe was US 3.84 million dollars during 2017, according to the
United Nations COMTRADE database on international trade.

Table 5-Pakistan phenol consumption according to imports value [CITATION COM \l

1033 ]

Annual
Import US
Year consumption
dollars
(metric ton/year)
2012 3913236 3913
2013 1740160 1740
2014 1964068 1964
2015 3060009 3060
2016 3570137 3570
2017 3845109 3845

Then annual consumption is based on the average phenol price of 1000 US dollars; however,
price may be different in different region of globe.

24
Chapter 01 Introduction

4500
4070
4000 3913 3845
3548 3570
3500

consumption (metric ton)

3060
3000 2890

2500
1964
2000 1740
1500 1189
1000

500

0
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017
Year

Figure 10-Phenol consumption in Pakistan

Total consumption of phenol in Pakistan (2017-2018) = 3845 MTY

Percentage increase in demand for Pakistan= 5 %
Increasing demand per year = 192 MTY
Increase in demand for 10 years = 1920 MTY
Total demand after 10 years = 5800 MTY
Working days = 300
Capacity of over plant = 20 MTD

Bibliography

25
Chapter 01 Introduction

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