(53b) Impact of Catalyst, Additives and Feedstock on Fcc Unit Performance

Fluid Catalytic Cracking (FCC) units are the most prevalent molecular weight reduction process in petroleum refineries. Traditionally, FCC units are used to convert heavy vacuum gas oil (the overhead product from vacuum distillation) to lighter products, principally gasoline. However, the modern FCC unit may often process feeds containing light atmospheric gas oils to those containing significant portions of high boiling residual fractions. Catalysts employed vary greatly, although all commercial FCC units today utilize catalysts containing a form of the zeolite faujasite as their primary active ingredient. However, smaller amounts of non-faujasitic materials, referred to as catalyst additives, may be blended with the base catalyst in order to impart special catalytic functionality or selectivity. This tutorial presentation reviews the different types of catalysts and catalyst additives commonly utilized in FCC units. Feed effects and feed interactions with the catalyst system are also discussed, including the impact of feed impurities such as nitrogen, sulfur, and metals.