Fossil fuels.
Extraction of oil

Petrochemistry: What is this branch of chemistry and what does it study?

Petrochemistry: What is this branch of chemistry and what does it study?

Petrochemicals is one of the branches of the chemical industry that deals mainly with the processing of petroleum derivatives and natural gas. The petrochemical industry is, among others, responsible for manufacturing automobile gasoline. 

Refineries are the petrochemical plants where these physical and chemical changes of these fossil fuels take place.

In this article, learn more about this industry and how it has contributed to modern technological development.

What is petrochemical?

Petrochemistry is the branch of chemistry dedicated to the study of compounds derived from petroleum and other hydrocarbons. This industry is responsible for the transformation of these compounds into chemical products used in various areas, such as agriculture, medicine or transportation.

Petrochemicals is divided into two large areas:

  • Petroleum chemistry focuses on the study of compounds derived from crude oil.

  • Natural gas chemistry deals with chemicals derived from natural gas as a feedstock.

What does petrochemistry study?

Petrochemistry studies the transformation of petroleum-derived compounds into other useful chemical derivatives.

This industry is responsible for the production of a wide variety of products, from detergents and fertilizers to plastics, synthetic fibers and elastomers.

What is crude oil?

The so-called crude oils are a group of diverse hydrocarbon compounds whose composition and appearance vary. The name of hydrocarbons comes from the two predominant chemical elements: carbon (84% on average) and hydrogen (14% on average).

Crude oils are classified based on sulfur content and can be sweet or bitter. Sour crude oils are high in sulfur content and may be in the form of hydrogen sulfides. On the other hand, sweets have less sulfur content.

The most important petrochemical processes

The most important petrochemical processes are:

1. Fractional Distillation of Crude Oil 

Fractional distillation is the process by which raw oil is separated into various segments. This process is carried out in a distillation tower, in which the crude oil is heated to a temperature between 400 and 600 °C.

The petroleum vapor that is produced expands and cools, which allows it to be separated into different fractions. The boiling point of the upper fractions is lower than that of the lower part. The bottom fractions are heavy and break down into lighter, more useful products.

2. The chemical crack of heavy hydrocarbons

Chemical crack takes place when heavy hydrocarbons are heated to high temperatures (700-1100 °C) in the presence of a catalyst. This causes the long chains of carbon to break into shorter chains, resulting in a higher yield of gasoline and other petroleum products.


Petrochemical products are also known as petroleum products because their manufacturing process uses petroleum as a primary source.

These substances are used to manufacture various types of fuels, lubricants, electrical insulating media, solvents, and raw materials.

The main products created by oil refining are:

  • Plastic

  • Asphalt: used as an aggregate agent in the production of bituminous conglomerates for road surfaces.

  • Fuel oils.

  • Automotive lubricants, motor oil and grease adding viscosity stabilizers where necessary.

  • Tar

  • Gaseous fuels such as propane, stored and distributed in liquid form.

  • Blended liquid fuels (such as specialty gasoline or aviation kerosene).

  • Paraffin, used as a component of candle wax and other uses.

  • Sulfur (or sulfuric acid), produced by the desulfurization of fuels.

  • Petroleum coke used as a solid fuel and for the manufacture of electrodes.

  • Basic products for the petrochemical industry.

By combining basic petrochemicals with other chemicals, intermediate products such as methanol-based resins, polyurethanes, and acetaldehydes can be obtained.

Publication Date: February 7, 2023
Last Revision: February 7, 2023