Some of the processes involved in crude oil refining are separation, conversion and treatment. The refined products derived from these processes include gasoline, diesel, kerosene, asphalt and liquefied petroleum gas.
At first, the refinery heats the crude oil until it vaporizes. The condensing gases are collected at different columns and highly viscous hydrocarbons such as bitumen are left at the bottom of the heating apparatus. During conversion, heavy hydrocarbon molecules are cracked into lighter molecules and most of the heavy products are converted to diesel, gasoline and gas. In the last stage, the refinery reduces or removes molecules that cause corrosion or air pollution, such as sulfur. Automotive fuels are further treated to increase resistance to detonation.