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Cracking of Petroleum

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While low molecular weight hydrocarbons suitable for use as fuels, feedstocks etc. are present in crude petroleum and could be separated by distillation, most of the hydrocarbons present in most crude oils are high molecular weight junk.

Cracking is the general term for breaking larger hydrocarbons into smaller hydrocarbons.

This is a picture of something that may be a catalytic cracker at a refinery in Shanghai

An artist's impression of hydrocarbon cracking, courtesy of the Chevron Corporation website

The cracking process is used to get smaller molecules by breaking up ("cracking") larger ones. Catalytic crackers are used to convert some of the fractions that come from refining crude oil to give us more useful molecules.

One of the most useful molecules to be made from cracking is ethene. (We're not just saying that because we're polymer chemists, it really is!) We'll meet ethene a little later and talk a bit about its structure and why it is so useful. For now, this is what ethene looks like:

The chemical structure of ethene.

NOTE: if you're not sure why it's call ethene, perhaps you should go through our nomenclature trail (open in new window).

To find out more about cracking, continue on...