Catalytic Cracking - continued.

The catalysts used in refinery cracking units are typically solid materials (zeolite, aluminum hydrosilicate, treated bentonite clay, fuller's earth, bauxite, and silica-alumina) that come in the form of powders, beads, pellets or shaped materials called extrudites.

Three basic processes take place in the catalytic cracking system:

a. Reaction: Feedstock reacts with catalyst and cracks into different hydrocarbons;

b. Regeneration: Catalyst is reactivated by burning off coke; and

c. Fractionation: Cracked hydrocarbon stream is separated into various products.

The three common types of catalytic cracking processes are fluid catalytic cracking (FCC), moving-bed catalytic cracking, and Thermofor Catalytic Cracking (TCC). The catalytic cracking process is very flexible, and operating parameters can be adjusted to meet changing product demand.