Petroleum in Industry
The petroleum industry produces a diverse range of materials that are essential to our
modern life. In its raw state petroleum offers no valuable function but through its
fractional distillation many important resources can be extracted. These chemicals,
resulting from the refinery of petroleum, are known as petroleum products or
petrochemicals. The most prominent application of petroleum products is in their use as
fuels; with petrol, LPG, diesel, kerosene (jet fuel) and fuel oils each being derived from
crude oil7. In turn these fuels may be employed to drive large industrial machinery,
provide energy for vehicles and supply basic heating. However petroleum products are
not limited to serving only as fuels. Pesticides, plastics, fibres, solvents, paints, glue,
fertilizers, pharmaceuticals, bitumen, asphalt, lubricants, synthetic rubbers and
explosives all use petroleum products as a feedstock. That is, petrochemicals are the
primary raw materials in each of the aforementioned products11.
In an engine a liquid fuel is used to supply combustible vapours. These vapours then
react with the oxygen in the air to combust, after being triggered by a spark, releasing
energy as heat. This release of energy is then utilised to supply energy to drive pistons in
the engines of vehicles and machinery; that is it is converted to mechanical energy7. (In
the case of heating, the reaction itself is sufficient in providing heat.) When a
hydrocarbon burns in the presence of oxygen it produces large amounts of heat in
addition to carbon dioxide and water, making hydrocarbons an ideal fuel5. The general
formula for the complete combustion reaction of a hydrocarbon is given:
C x H y (g) + ( x + )O 2(g) → ( )H 2 O (g) + xCO 2(g) + Heat
Fuel + Oxygen → Water + Carbon dioxide +Heat
As can be seen from this equation, the quantity of oxygen consumed and quantities of
water and carbon dioxide produced is dependent on the length of the carbon chain.
The amount of heat produced from the combustion of a hydrocarbon also depends
upon this, as well as its structure6. Because hydrocarbon compounds have various
properties, not all hydrocarbons are practical sources of energy and many fuels have
distinct purposes and are used only in specialised roles.
The diagram below illustrates the four stage process of the modern internal
combustion engine of a car. Initially a small amount of fuel with a relatively larger
quantity of air is injected into the chamber. The fuel vaporises and mixes with the air.
This mixture is then compressed and following this, a spark plug is fired, resulting in
the combustion of the fuel and oxygen. In the final stage the produced water vapour
and carbon dioxide is ejected from the chamber4.
Figure 1 
Petrol, a mixture of alkanes with carbon chains between 6 and 12, is perhaps the most
well know fuel. It’s a relatively volatile substance allowing it to provide sufficient
vapours for combustion at a range of temperatures7. It is therefore primarily used in the
internal combustion engines of cars .The main constituents of petrol are aliphatic
compounds of which octane is the most abundant but also present are aromatics such
as benzene and toluene7. The combustion of octane is the main reaction that takes
place in car engines and is given below.
Complete balanced equation:
2C 8 H 18(g) + 25 O 2(g) → 18H 2 O (g) + 16CO 2(g)
Equation for combustion of one mole of octane:
C8 H18(g) + 12 O 2(g) → 9H 2O (g) + 8CO 2(g) ∆H = -5468.49KJ/mol
The equation above shows that for every one mole of octane burned, it releases nearly
5500 KJ of energy. Or, considering the molar mass of octane, 114g/mol, it can be
calculated that each gram of octane produces 47.96 KJ.
Diesel fuel is typically give the formula C14H30 but can contain hydrocarbon chains with
up to 18 carbons. Diesel fuel is used to operate diesel engines, which vary slightly from
modern car engines1. Air is compressed prior to the injection of fuel and therefore there
is no need for a spark. The combustion of diesel fuel is given:
C14 H 30(g) + 21 O 2(g) → 15H 2 O (g) + 14CO 2(g) ∆H = -8712KJ/mol
Diesel engines are actually more fuel efficient and are employed mostly in the
transportation of cargo1.
Non Fuel Petroleum Products:
Petroleum products account for far more than just the fuel industry; although this is
undoubtedly their primary function. In fact many byproducts from the manufacture of
fuels are used to produce a diverse range of versatile materials11.
Petroleum Jelly consists of paraffins with carbon chains above 25. Also know as soft
paraffin it is has a number of potential applications. As a saturated hydrocarbon it is
resistant oxidation and is used as a coating on metals to prevent this, having a sealing
effect13. Similarly it is used medicinally and cosmetically to protect the skin and prevent
infection of open wounds. Furthermore the greasiness of petroleum jelly lends its self
well to lubricating mechanical cogs13.
Lubricating oils are a hydrocarbon blend of chains just below 20 carbons. They do not
vaporise at standard temperatures as do other petrochemicals, such as kerosene and
petrol. Lubricating oils prevent wear from occurring between moving parts of
equipment and reduce the loss of energy through friction. Longer chain lengths result in
a higher viscosity of the liquid and further enhance the lubricating properties3.
Additionally petrochemicals supply stable and cheap lubricants3. The hydrocarbons
around these lengths (20 Carbons) vaporise at temperatures only above 121˚C and are
therefore suited to lubricating car gears and other machinery that operate at high
Petrochemicals form the basis of plastics. The raw petroleum is refined into ethane and
propane. These hydrocarbons are then subjected to catalytic cracking and are ‘cracked’
into propylene and ethylene. These monomers are then polymerized (fig.2) into their
respective polymers by placing them each into a reactor with a catalyst11.
Figure 2 
These polymers are melted and then shaped, from this point they can then be
manufactured into a variety of products such as car parts, toys, components of housing
and various other items11. Poly-propylene and poly-ethylene are not the only polymers
that become plastics; polystyrene (fig.3) is perhaps the most versatile of all plastics and
is too derived from petroleum products11.
Figure 3 
Solvents operate on the principle that like dissolves like8. Petrochemicals such as
benzene are therefore ideal for dissolving greasy, oil based build up. Subsequently most
oven and kitchen cleaners contain at least one petrochemical. All solvents apart from
alcohol are derived from petroleum; paraffinic, aliphatic and aromatic hydrocarbons are
all used as solvents12.
Kerosene, most notably used in jet engines as a fuel base and as the oil in heating lamps,
has several more applications and is representative of the versatility of petroleum
Jet fuel is not solely comprised of kerosene. Whilst this is the main constituent many
additives such a benzene and toluene are added to increase the favourable properties of
kerosene, which includes its resistance to gelling (process of slowly solidifying).
As a jet and rocket fuel kerosene works similarly to petrol in a car engine. The same
principles apply; jet engines (gas turbines) use the combustion of kerosene (among
other fuels) with air to achieve motion. The high enthalpy of kerosene means the jet is
able to quickly expend energy, which is a desirable trait in gas turbines. The exact
process differs from an internal combustion engine9. Jet engines do not use pistons and
instead operate on thrust, the fuel is still burned in order generate energy but the aim is
to directly propel the craft forward9. The chemical equation for the combustion of
kerosene is provided:
C12 H 26(g) + O 2(g) → 12H 2O (g) + 13CO 2(g) ∆H = -7513KJ/mol
Although the energy per unit mass is lower than that of petrol at 44.19KJ/g; the higher
resistance to gelling, its cheaper cost and higher enthalpy make kerosene a more
Kerosene was the staple fuel of lamps prior to electricity. It has since become more
common for kerosene to be used as heating oil for small camp stoves9. The combustion
of kerosene is used to supply heat energy to the stove and subsequently the food. In
Japan Kerosene is used extensively as a fuel for heating houses, again this operates on
the combustion of kerosene.
Kerosene is an excellent solvent for dissolving grease and tar as it has similar properties
as a petroleum product. This follows from like dissolving in like and is thus a superior
solvent to water for organic compounds8.
Kerosene due to its lower density than water (and a specific gravity of about 0.81) is
sometimes used to exterminate mosquito populations in the larval stages9. A thin layer
of Kerosene is expelled over the surfaces of small ponds in order to starve mosquito
larvae of oxygen9.
Environmental issues resulting from the use of kerosene are similar to those of any
petrochemical. Kerosene is toxic if swallowed and its combustion, which is effected in a
majority of ways, contributes to CO2 emissions9. Notably, but often overlooked, is the
detrimental affect of water vapour and its contribution to the greenhouse effect, largely
outweighing that of CO2. Its production is an additional byproduct of the burning of
Kerosene9. Obvious concerns are raised from kerosene’s use as a pesticide, including
endangering other wildlife and flora. As heating oil, Kerosene use lead to several fires
and proved hazardous in most circumstances.
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