2014
Review on reversible and irreversible FCC catalyst deactivation.
The main cause of deactivation is coke deposition. The rate of coking depends on the feed. Many types of coke are distinguished. Mechanisms and kinetics are discussed. Basic nitrogen and sulphur in unsaturated rings may end up in the coke, which form NOx/SOx if the coke is removed by burning off with air.
Hydrothermal deactivation by steam at 650-800°C can be fast, depends on the zeolite used, and it is irreversible. Rare earth metals and phosphorus improve the hydrothermal stability. Ni and V act as poisons of the zeolite active sites, but there are ways to avoid that happening. Also Fe, Ca, and Na can cause deactivation.
