流化催化裂化（FCC）是炼油厂中最重要的转化工艺之一。它广泛用于将原油中高沸点、高分子量的馏分转化为更有价值的汽油、烯烃气体和其他产品。 石油烃类的裂化最初都是热裂解，现在已几乎全部被催化裂化取代，因为它可以生产更多高辛烷值的汽油。它还副产更多的烯烃气体，所以它比热裂解生产的更有价值。

FCC的进料通常是原油中初馏点为340°C或更高（常压）以及平均分子量在200到600或更高的部分。这部分原油通常称为重瓦斯油或减压瓦斯油（HVGO）。FCC工艺是在高温和适当压力下与流化粉末催化剂接触，使原料汽化并将高沸点长链的烃分子断开成短得多的分子。

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.