Petrochemical Products

Petrochemicals are chemicals manufactured from crude oil and natural gas as distinct from fuels and other products, derived from crude oil and natural gas, and used for a variety of commercial purposes.

The definition has been broadened to include the whole range of organic chemicals. In many instances a specific chemical included among the petrochemicals may also be obtained from other sources, such as coal, coke, or vegetable products. For example, materials such as benzene and naphthalene can be made from either crude oil or coal, while ethyl alcohol may be of petrochemical or vegetable origin.

However, in the current context, petrochemicals can be conveniently divided into two groups:
(1) primary petrochemicals and
(2) intermediates and derivatives.

Primary petrochemicals include
(1) olefin derivatives, such as ethylene and propylene and butadiene;
(2) aromatic derivatives, such as benzene, toluene, and the xylene isomers; and
(3) methanol.

Petrochemical intermediates are generally produced by chemical conversion of primary petrochemicals to form more complicated derivative products.

Petrochemical derivative products can be made in a variety of ways:
- directly from primary petrochemicals;
- through intermediate products which still contain only carbon and hydrogen; and
- through intermediates that incorporate chlorine, nitrogen, or oxygen in the finished derivative.

In some cases, they are finished products; in others, more steps are needed to arrive at the desired composition.