Crude oil is a mix of hydrocarbons that can be processed to give us petrochemicals including synthetic alternatives to natural materials (rubber) and unique materials such as nylon. Petrochemistry is a fairly young industry; it only started to grow in the 1940s, more than 80 years after the drilling of the first commercial oil well in 1859. During World War II, the demand for synthetic materials to replace costly and sometimes less efficient products caused the petrochemical industry to grow.

Petrochemistry gets its feedstock (raw material) from the refinery: naphtha, components of natural gas such as butane, and some of the by-products of oil refining processes, such as ethane and propane. These feedstocks are then processed through an operation that is known as cracking. Cracking is simply the process of breaking down heavy hydrocarbon molecules into lighter, more valuable fractions. In steam cracking, high temperatures are used; when a catalyst is used it is known as catalytic cracking.

Once these operations are concluded, new products are obtained, the building blocks of the petrochemical industry: olefins (ethylene, propylene) and aromatics (benzene, toluene, and the xylenes). These products are processed in petrochemical plants into other, more specialized products to be used by the so-called downstream industries, the customer industries of petrochemistry.

ethylene trash bags, packaging
propylene packaging, plastic lids
benzene solvents, resins, nylon
toluene high-octane fuel, polyurethane
xylenes polyester fabric

In the end, petrochemicals will go into products that we are all familiar with: plastics, soaps and detergents, healthcare products such as aspirin, synthetic fibers for clothes and furniture, rubber, and paints.


  1. 7.1 Petrochemical fabric test
    Which fiber is best for swimsuits?
  2. 7.2 Materials and their properties
    How might you design a test for a petrochemical product?


Describe a day without oil.

Digital extras