Fluid catalytic cracking (FCC) is one of the most important conversion processes used in
petroleum refineries. It is widely used to convert the high-boiling, high-molecular weight
hydrocarbon fractions of
petroleum crude oils to more valuable
gasoline,
olefinic gases, and other products. Cracking of petroleum hydrocarbons was originally done by
thermal cracking, which has been almost completely replaced by catalytic cracking because it produces more gasoline with a higher
octane rating. It also produces byproduct gases that are more olefinic, and hence more valuable, than those produced by thermal cracking.