Fluid catalytic cracking

Fluid catalytic cracking converts heavy petroleum fractions into lighter hydrocarbons by contacting them with finely powdered catalyst that circulates between a reactor and a regenerator.

Riser reactor: A vertical conduit where catalyst particles and hydrocarbon vapors mix and react rapidly. Most cracking occurs as feed vapor and hot catalyst rise together through this reactor.
Vacuum gas oil: A heavy petroleum fraction obtained by vacuum distillation of atmospheric residue. It is a common feed whose large molecules are converted into lighter products.
Petroleum refining: The industrial processing of crude oil into fuels, petrochemical feedstocks, and other products. Fluid catalytic cracking is a major conversion unit within an integrated refinery.
Thermal cracking: The breaking of hydrocarbon molecules by heat without a solid acid catalyst. It produces lighter hydrocarbons through heat-driven reactions rather than circulating catalyst particles.
Zeolite catalyst: A porous crystalline aluminosilicate whose acid sites catalyze hydrocarbon reactions. Its pores and acid sites promote selective cracking of large hydrocarbon molecules.
Hydrocarbon cracking: The breaking of carbon–carbon bonds in large hydrocarbons to form smaller molecules. Fluid catalytic cracking is a catalytic, refinery-scale form of this broader chemical transformation.
Refinery gas: A mixture of light gases produced and recovered during petroleum refining. Cracking yields gases such as propylene and butenes that can feed further processing.
Hydrocracking: A catalytic process that cracks heavy hydrocarbons in the presence of hydrogen. Unlike fluid catalytic cracking, it consumes hydrogen and typically produces more saturated products.
Catalyst regeneration: A process that restores catalyst activity by burning off deposited carbonaceous material. Regeneration removes coke and supplies heat before catalyst returns to the reactor.
Carbocation: An organic ion containing a positively charged carbon atom. Acid-catalyzed cracking proceeds through carbocation intermediates that rearrange and fragment.

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