INDEX

ACKNOWLEDGMENT
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CERTICICATE

INTRODUCTION
WHAT IS PETROLEUM?-1
HOW IS PETROLEUM FORMED?- 2-3
WHERE IS THE PETROLEUM?-4
HOW DO WE USE THE PETROLEUM?-5-7
STRUCTURE IF PETROLEUM?-8-12
REFINING OF PETROLEUM-13-16
PRODUCTS OF REFINING PROCESS-17-18
CONCLUSION-19
ACKNOWLEDGMENT
I have taken efforts in this project under
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the guidance of Mr.Ravindra Reddy sir,
and my principle. Thanks to both of
them for supporting me in its
completion.

I am grateful towards my friends and my

family for assisting me in this project in
every possible way.

At last, I would like to extend my sincere

gratitude towards the almighty SCIENCE
COMMUNITY which works hard
everyday to let us kids investigate these
theories and move closer towards
unraveling the mysterious of nature.
 CERTIFICATE
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This is to certify that this chemistry
project on “PETROLEUM” has been
completed by Stuti Jain of XI science in
the academic year of 2023-24 under the
guidance of Mr. Ravindra Reddy sir for
partial fulfillment of the chemistry
practicale examination conducted by
AISSCE, Ner Delhi

INTERNAL EXTERNAL PRINCIPAL

EXAMINER EXAMINER SIGNATURE
 INTRODUCTION
What is Petroleum?
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Petroleum is referred to as “Black Gold.” This
name itself is an indication of its importance to
humans. Crude oil is considered to be the
“mother of all commodities” as it is used to
manufacture various products such as
pharmaceuticals, plastics, gasoline, synthetic
fabrics, etc. Petroleum or oil has also been the
world’s leading source of energy since the 1950s.
Petroleum is a liquid which occurs naturally in
rock formations. This consists of a complex
mixture of different molecular weights of
hydrocarbons, plus other organic compounds.
Some petroleum-produced chemical compounds
are also obtained from other fossil fuels.
Petrochemicals are produced mainly at a few
manufacturing sites around the world. Petroleum
is also the raw material for many industrial
products, including pharmaceuticals, solvents,
fertilizers, pesticides, synthetic fragrances, and
plastics.
 How is Petroleum Formed?

Step 1: Diagenesis forms Kerogen

Diagenesis is a process of compaction under mild conditions
of temperature and pressure. When organic aquatic
sediments (proteins, lipids, carbohydrates) are deposited,
they are very saturated with water and rich in minerals.
Through chemical reaction, compaction, and microbial action
during burial, water is forced out and proteins and
carbohydrates break down to form new structures that
comprise a waxy material known as “kerogen” and a black tar
like substance called “bitumen”. All of this occurs within the
first several hundred meters of burial.
The bitumen comprises the heaviest components of
petroleum, but the kerogen will undergo further change to
make hydrocarbons and, yes, more bitumen…
 Step 2: Catagenesis (or “cracking”) turns kerogen into
petroleum and natural gas
As temperatures and pressures increase (deeper burial) the
process of catagenesis begins, which is the thermal
degradation of kerogen to form hydrocarbon chains.
Importantly, the process of catagenesis is catalyzed by the
minerals that are deposited and persist through marine
diagenesis. The conditions of catagenesis determine the
product, such that higher temperature and pressure lead to
more complete “cracking” of the kerogen and progressively
lighter and smaller hydrocarbons. Petroleum formation, then,
requires a specific window of conditions; too hot and the
product will favor natural gas (small hydrocarbons), but too
cold and the plankton will remain trapped as kerogen.

This behavior is contrary to what is associated with coal

formation. In the case of terrestrial burial, the organic
sediment is dominated by cellulose and lignin and the
fraction of minerals is much smaller. Here, decomposition of
the organic matter is restricted in a different way. The
organic matter is condensed to form peat and, if enough
temperature (geothermal energy) and pressure is supplied, it
will condense and undergo catagenesis to form coal. Higher
temperatures and pressures, in general, lead to higher ranks
of coal.
 Where is the petroleum?

Because the earth is filled entirely by layers of solid (or at

significant depths) molten rock, the petroleum it contains cannot
exist within a self-contained “lake”, but must decide to live within
the small fraction of space (or pores) that exist in these rocks. Like
the sponge in your kitchen sink (albeit, less spongy and a bit
heavier) certain kinds of rock (mainly sandstone and limestone)
contain pores large enough and with enough connections to serve
as storage and migration sites for oil or water or any other fluid
wishing to call them home. Because most hydrocarbons are lighter
than water and rock, those that exist within the earth will tend to
migrate upwards until they reach the surface, or are trapped by an
impermeable layer of rock.
There is a particular window of temperature that the zooplankton
must find to form oil. If it is too cold, the oil will remain trapped in
the form of kerogen, but too hot and the oil will be changed
(through “thermal cracking”) into natural gas. Therefore, the
formation of an oil reservoir requires the unlikely gathering of
three particular conditions: first, a source rock rich in organic
material (formed during diagenesis) must be buried to the
appropriate depth to find a desirable window; second, a porous
and permeable (connected pores) reservoir rock is required for it
to accumulate in; and last a cap rock (seal) or other mechanism
must be present to prevent it from escaping to the surface. The
geologic history of some places on earth makes them much more
likely to contain the necessary combination of conditions.
 How do we use the petroleum?

To be of use to us, the crude oil must be “fractionated” into its

various hydrocarbons. This is done at the refinery.
Oil can be used in many different products, and this is because
of its composition of many different hydrocarbons of different
sizes, which are individually useful in different ways due to their
different properties. The purpose of a refinery is to separate
and purify these different components. Most refinery products
can be grouped into three classes: Light distillates (liquefied
petroleum gas, naphtha, and gasoline), middle distillates
(kerosene and diesel), and heavy distillates (fuel oil, lubricating
oil, waxes, and tar). While all of these products are familiar to
consumers, some of them may have gained fame under their
refined forms. For instance, naphtha is the primary feedstock
for producing a high octane gasoline component and also is
commonly used as cleaning solvent, and kerosene is the main
ingredient in many jet fuels.
In a refinery, components are primarily separated using “fractional
distillation”. After being sent through a furnace, the crude
petroleum enters a fractionating column, where the products
condense at different temperatures within the column, so that the
lighter components separate out at the top of the column (they
have lower boiling points than heavier ones) and the heavier ones
fall towards the bottom. Because this process occurs at
atmospheric pressure, it may be called atmospheric distillation.
Some of the heavier components that are difficult to separate may
then undergo vacuum distillation (fractional distillation in a
vacuum) for further separation. The heaviest components are then
commonly “cracked” (undergoing catagenesis) to form lighter
hydrocarbons, which may be more useful. In the same manner that
natural mineral catalysts help to transform kerogen to crude oil
through the process of catagenesis, metal catalysts can help
transform large hydrocarbons into smaller ones. The modern form
of “catalytic cracking” utilizes hydrogen as catalyst, and is thus
termed “hydrocracking”. This is a primary process used in modern
petroleum refining to form more valuable lighter fuels from
heavier ones. All of the products then undergo further refinement
in different units that produce the desired products.
Alkanes are saturated hydrocarbons with between 5 and 40
carbon atoms per molecule which contain only hydrogen and
carbon. The light distillates range in molecular composition from
pentane (5 carbons: C5H12) to octane (8 carbons: C8H18). Middle
distillates range from nonane (9 carbons: C9H20) to hexadecane
(16 carbons: C16H34) while anything heavier is termed a heavy
distillate. Hydrocarbons that are lighter than pentane are
considered natural gas or natural gas liquids (liquefied petroleum
gas).
 A few further refinement processes are described below:
· Desalting removes salt from crude oil before entering fractional
distillation.
· Desulfurization removes sulfur from compounds, and several
methods are possible. Hydrodesulfurization is the typical method, and
uses hydrogen to extract the sulfur. This occurs after distillation.
· Cracking breaks carbon-carbon bonds to turn heavier
hydrocarbons into lighter ones. This can occur thermally (as occurs
during the petroleum formation process beneath the earth) or through
the action of a catalyst:
o Thermal Cracking
§ Steam, visbreaking, or coking
o Catalytic cracking
Fluid catalytic cracking (FCC) cracks heavy oils into diesel and gasoline.
Uses a hot fluid catalyst.
Hydrocracking (similar to FCC but lower temperature and using
hydrogen as catalyst) cracks heavy oils into gasoline and kerosene
· A catalytic reformer converts naphtha into a higher octane form,
which has a higher content of aromatics, olefins, and cyclic
hydrocarbons. Hydrogen is a byproduct, and may be recycled and used
in the naphtha hydrotreater.
· Steam reforming is a method of producing hydrogen from
hydrocarbons, which may then be used in other processes.
· Solvent dewaxing removes heavy wax constituents from the
vacuum distillation products.
 STRUCTURE OF PETROLEUM

Usually the fuels used in internal combustion engines are complex

mixtures of hydrocarbons made by refining petroleum. Petroleum
as obtained from the oil wells is predominantly a mixture of many
hydrocarbons with differing molecular structure. It also contains
small amounts of sulphur, oxygen, nitrogen and impurities such as
water and sand. The carbon and hydrogen atoms may be linked in
different ways in a hydrocarbon molecule and this linking
influences the chemical and physicalproperties of different
hydrocarbongroups. The carbon to hydrogen ratio which isone of
the important parameters and their nature of bonding determine
the energycharacteristics of the hydrocarbon fuels. Depending
upon the number of carbon and hydrogen atoms the petroleum
products are classified into different groups.
They are
(i) Paraffin series ( CnH2n+2 )
(ii) Olefin series ( CnH2n )
(iii) Naphthene series (CnH2n)
(iv) Aromatic series (CnH2n-6)
 (i) Paraffin series
The normal paraffin hydrocarbons are of straight chain
molecular structure. They are represented by a general
chemical formula CnH2n+2, where n is number of carbon
atoms. In these hydrocarbons the valency of all the carbon
atoms is fully utilized by single bonds with hydrogen atoms.
Therefore the paraffins hydrocarbons are saturated
compounds and their characteristics are very stable. The
name of each member ends in 'ane' as in methane, propane,
hexane, etc. n-Propane means normal propane.

A variation of the paraffin family consists of an open chain structure

with an attached branch and is usually termed a branched chain
paraffin. The hydrocarbons which have the same chemical formulae
but different structural formulae are known as isomers.

Isobutane shown above has the same general chemical formula and
molecular weight as butane but a different molecular structure and
physical characteristics. It is called as isomer of butane and is known
as isobutane. Isoparaffins are also stable compounds. The lower
paraffins are gases, the higher being liquids and still higher, solids.
 ii) Olefin series:
Olefins are also straight chain compounds similar to
paraffins but are unsaturated because they contain one
or more double bonds between carbon atoms.
The names of hydrocarbons having one double bond
end in lene' as in ethylene, butene, etc., and in `adiane'
for two double bonds as in butadiene, etc

Hexene Butadiene

The general formulae are CnH2n for mono-olefins (one double-

bond) and CnH2n-2 for the diolefins (two double-bonds).

(iii) Naphthene series

The naphthenes have the same chemical formula as the
olefin series of hydrocarbons but have a ring structure and
therefore often they are called as cyclo-paraffins. They are
saturated and tend to be stable.

Cyclopentane
 iv) Aromatic Series
Aromatic compounds are ring structured having a
benzene molecule as their central structure and have a
general chemical formula CnH2n-6. Though the
presence of double bonds indicates that they are
unsaturated, a peculiar nature of these double bonds
causes them to be more stable than the other
unsaturated compounds.

Benzene Toluene

Various aromatic compounds are formed by

replacing one or more of the hydrogen atoms of
the benzene molecules with an organic radical
such as paraffins, naphthenes and olefins. By
adding a methyl group (CH3). Benzene is converted
to toluene ( C6H5CH3 ) the base for the
preparation of Trinitrotoluene (TNT) which is a
highly explosive compound.
 General characteristics of hydrocarbon due to the
molecular structure:

 Normal paraffins exhibit the poor antiknock quality

when used in an SI engine. But the antiknock quality
improves with the increasing number of carbon
atoms and the compactness of the molecular
structure. The aromatics offer the best resistance to
knocking in SI Engines.
 For CI engines, the order is reversed i.e., the normal
paraffins are the best fuels and aromatics are the
least desirable.
 As the number of atoms in the molecular structure
increases, the boiling temperature increases. Thus
fuels with fewer atoms in the molecule tend to be
more volatile.
 The heating value generally increases as the
proportion of hydrogen atoms to carbon atoms in the
molecule increases due to the higher heating value of
hydrogen than carbon. Thus paraffin’s have the
highest heating value and the aromatics the least.
 REFINING OF PETROLEUM

The process of (i) removing impurities and (ii)

separating petroleum into more useful fractions with
different boiling point range is known as refining of
petroleum.

(i) Removal of impurities:

Step 1: Separation of Water (Cottrell’sProcess) The

crude oil from the oil well is an extremely stable
emulsion of oil and salt water. The process of freeing
oil from water consists in allowing the crude to flow
between two highly charged electrodes. The colloidal
water droplets coalesce to form large drops, which
separate out from the oil.

Step2: Removal of harmful sulphur compounds It

involves in treating oil with copper oxide. A reaction
occurs with sulphur compounds, which results in the
formation of copper sulphide, which is then removed
by filtration.
 (ii) Fractional distillation

The crude oil is separated into gasoline, kerosene, fuel oil etc. by the
process of fractional distillation. In the first step, the petroleum is
passed through a separator in which the gases are removed and a
product known as natural gasoline is obtained. The liquid petroleum is
then vapourized in a still, at temperatures of 6000C and the vapour is
admitted at the bottom of the fractionating tower. The vapour is
forced to pass upwards along a labyrinth like arrangement of plates
which direct the vapour through trays of liquid fuel maintained at
different temperatures. The compounds with higher boiling points get
condensed out at lower levels while those with lower boiling points
move up to higher levels where they get condensed in trays at
appropriate temperature. Generally the top fraction is called the
straight run gasoline and the other fractions, kerosene, diesel oil, fuel
oil etc., are obtained in the increasing range of boiling temperatures.

The gasoline demand is much more than that of other petroleum

products. This led to the development of refinery processes to
convert unwanted streams of crude into salable products and to
upgrade quality of these streams. Many processes can be used to
convert some of these fractions to compounds for which there is a
greater demand
 Some of the main refinery processes are as follows

(i) Cracking consists of breaking down large and complex

hydrocarbon molecules intosimplercompounds. Thermal cracking
subjects the large hydrocarbon molecules to high temperature and
pressure and they are decomposed into smaller, lower boiling point
molecules.

(ii) Catalytic cracking using catalysts is done at a relatively lower

pressure and temperature than the thermal cracking. Due to catalysis,
the naphthenes are cracked to olefins, paraffins and olefins
toisoparaffins needed for gasoline. Catalytic cracking gives better
antiknock property for gasoline as compared to thermal cracking.

(iii) Hydrogenation consists of the addition of hydrogen atoms to

certain hydrocarbonsunder high pressure and temperature to
produce more desirable compounds. It is often used to convert
unstable compound to stable ones
.
(iv) Polymerization is the process of converting olefins, the
unsaturated products of cracking, into heavier and stable
compounds.

(v) Alkylation combines an olefin with an isoparaffin to produce a

branched chain isoparaffin in the presence of a catalyst.
(vi) Isomerization changes the relative position
of the atoms within themolecule of a
hydrocarbon without changing its molecular
formula. For example, isomerization is used for
the conversion of n-butane into isobutane for
alkylation. Conversion of npentane and n-
hexane intoisoparaffins to improve knock rating
of highly volatile gasoline is another example.

(vii) Cyclization joins together the ends of a

straight chain molecule to form a ring
compound of the naphthene family.

(vii) Aromatization is similar to cyclization, the

exception being that the product is an aromatic
compound.

(viii) Reformation is a type of cracking process

which is used to convert the low antiknock
quality stocks into gasoline of higher octane
rating. It does not increase the total gasoline
volume.

(ix) Blending is a process of obtaining a product

of desired quality by mixing certain products in
some suitable proportion.
 PRODUCTS OF REFINING PROCESS:

(i) Natural Gas: Natural gas is found dissolved in petroleum or in huge amounts under
earth surface inoil and gas bearing areas. Natural gas is made up mainly of the paraffinic
compoundmethane, a small amount of propane, ethane, butane and other light
hydrocarbons plus some nitrogen and oxygen. When natural gas occurs along with
petroleum in oil wells, it is called wet gas. On the other hand, when the gas is associated
with crude oil, it is called dry gas.

Uses:  It is an excellent domestic fueland can be conveyed over very large distances in
pipelines.  It has been recently used in the manufacture of a number of chemicals by
synthetic processes

(ii) LPG: Liquefied petroleum gas (LPG) or bottled gas or refinery gas is obtained as a
byproduct, during the cracking of heavy oils or from natural gas. It is stored in liquid form
in special cylinders at a pressure of about 100psi (700 kpa) and the engine is provided
with a special fuel system. Its calorific value is about 27800 kcal/m3 . The main
constituents of LPG are n-butane, isobutane, butylene and propane, with little or no
propylene and ethane.

Advantages:
 Better mixing with air and improved distribution, which means lesseremissions.
 No need of a fuel pump.
 No carbon deposits.
 No crank case dilution because of vapour form. This means lesser oil consumption.
 High octane rating.
 Less engine wear.

Disadvantages:
 Special fuel system has to be provided.
 Heavy pressure cylinders increase the vehicle weight unnecessarily.
 Hard to start in winter.

(iii) Gasoline Gasoline is the lightest liquid petroleum fraction. All material boiling
up to 200°C is generally considered as gasoline. This is mixture of a number of
hydrocarbons (more than 40). The composition depends upon the crude oil and
refining process. Gasoline lies in specific gravity range 0.70 to 0.78. This covers
most of fuels used for spark-ignition engines. Its calorific value is about 47102 kJ/kg

(iv) Kerosene. The kerosene has heavy fraction than gasoline. Its boiling range is
150°C to 300°C and the specific gravity range is 0.78 to 0.85.Its calorific value is
about 46474 kJ/kg
 (v) Distillate. The distillate is slightly heavier
than kerosene. These are used as tractor fuels
and domestic fuels.

(vi) Diesel Oils. Diesel oils are fuels which lie

between kerosene and lubricating oils. These
cover a wide range of specific gravity and boiling
point. Boiling range is 200 to 370°C. These form
the fuels for compression ignition engines.

(vii) Fuel Oils. Fuel oils are similar to diesel fuel

in specific gravity and distillation range but their
composition varies in a range wide than those of
diesel fuels. These are used as industrial fuels.

(viii) Lubricating Oils. Lubricating oils are made

up of heavy distillate of petroleum and residual
oil. These are used for lubricating purposes.

(ix) Tar and Asphalt. Tar and asphalt are solid or

semi-solid undistilled products of petroleum.

(x) Petroleum Coke. Petroleum coke is used as

solid industrial fuel
 Conclusion

Petroleum is a naturally occurring, dark

brown to a black mixture of hydrocarbons
that can be refined into various types of
fuels. The word petroleum comes from Latin
and means "rock oil." Petroleum has many
uses including providing light in kerosene
lamps, lubricating machinery with motor oil,
powering cars with gasoline or diesel fuel,
and heating homes with home heating oil. It
is also used as the raw material for many
chemical products such as solvents (e.g.,
paint thinner), brake fluid, asphalt
pavement sealer, and roofing tar among
others.

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