Petrochemicals
Naphtha is the most important primary distillation product. It is used as raw material for the production of gasoline, ethylene, propylene and aromatics.
Aromatics are separated from other components by extraction.
The major pure hydrocarbons produced from crude oil in order to serve as the building blocks of the petrochemical industry are:
Ethylene
Propylene
Butenes
Benzene
Toluene
Xylenes
Natural substances have been proposed as raw materials for the petrochemical industry. The most important one is sugar which has been used to derive many petrochemicals, but not in reasonable prices. Acetylene which can be made from coal was the main raw material for petrochemicals in Germany during the second world war.
Synthesis gas: mixtures of CO and hydrogen is an important raw material. It is produced today by the partial oxidation of methane or naphtha for the production of methanol, acetic acid and ammonia. It can be produced by the reactions of coal with oxygen and steam. It can be used to produce petrochemicals or gasoline. Many processes have been developed for these puposes, but only a few are in current use, due to the low crude price (till recently).