Well... It is more that a traditional oil refinery has a BTX section https://en.wikipedia.org/wiki/BTX_(chemistry) https://en.wikipedia.org/wiki/BTX_(chemistr

Well... It is more that a traditional oil refinery has a BTX section https://en.wikipedia.org/wiki/BTX_(chemistry) https://en.wikipedia.org/wiki/BTX_(chemistry) which produces an excess of chemicals in the process of improving the octane of gasoline https://en.wikipedia.org/wiki/Catalytic_reforming https://en.wikipedia.org/wiki/Catalytic_reforming and that is where you get monomers like styrene and Terephthalic acid. https://en.wikipedia.org/wiki/Ethylene https://en.wikipedia.org/wiki/Ethylene is another important petrochemical feedstock which can be made from natural gas or other forms of petroleum.