Lamia Dahmash and Shinhoo Lee

Crude oil (or petroleum) was formed over the course of millions of years from the decay of marine organisms. Crude oil is a mixture of different hydrocarbons and they can be separated or refined, and most of the crude oil is used for sources of energy such as petrol, other fuels for transport (diesel), and oil heating systems.. Only 10% of crude oil is used as chemical feedstock. Chemical feedstock is used to manufacture products such as polymers, drugs, cosmetics, paints, fertilizers, pesticides, detergents and dyes.

Cracking is the process conducted at high temperatures whereby large hydrocarbons are broken down into smaller, more useful molecules. The products are usually alkanes and alkenes. For example, decane can be broken down from octane to ethene. C 10 + H 22 (g) C 8 H 18 (g) + C 2 H 4 (g) The alkanes are usually branched isomers (eg.2,2,4 trimethyl pentane) and are added to gasoline (petrol) to improve the octane rating. The alkanes are used to make other chemicals, particularly addition polymers.

The use of a Silica/ alumina Catalyst enables the cracking to take place at relatively low temperature of between ° C. Products are branched alkanes and alkenes. An example is high grade gasoline, since branched alkanes increase the fuel octane rating

The feedstock preheated, vaporized, and mixed with steam and then converted to low molecular mass alkenes at ° C. These are used in manufacturing of polymers (i.e. polyethene)

Temperatures range from ° C, and a high pressure of 70 atm is required. This process creates branched alkanes and alkenes, but smaller hydrocarbons than those produced by catalytic cracking. Used for kerosene, jet fuel.

The number of Carbon atoms, boiling ranges, and the uses of different fractions summarized in the table:

FractionCarbon Chain LengthBoiling Range / °CMain Uses Refinery Gas1-4<30Used as fuel on site, gaseous cooking fuel, and as feedstock for chemicals, e.g.. Methane is used to provide hydrogen gas for the Haber process. Gasoline Gasoline (petrol) for cars. Feedstock for organic chemicals (by steam cracking). Kerosine Fuel for jet engines. Domestic heating cracked to provide extra gasoline (petrol). Gas oil (Diesel oil) Diesel engines and industrial heating; cracked to produce extra gasoline (petrol). Residue> 20>350Fuel for large furnaces; vacuum distilled to make lubricating oils and waxes. Residue of Bitumen and asphalt used to surface roads and waterproof roofs.

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