Catalytic cracking, general coke, composition

Petroleum coke is the residue left by the destructive distillation (thermal cracking or coking) of petroleum residua. The coke formed in catalytic cracking operations is usually nonrecoverable because of adherence to the catalyst, as it is often employed as fuel for the process. The composition of coke varies with the source of the crude oil, but in general, is insoluble on organic solvents and has a honeycomb-type appearance. 

---