Catalyst design for resid cracking operation: Benefits of metal tolerant technologies

FCC cracking operations that process resid-type feedstocks are often faced with the dilemma of managing significant levels of contaminant metals on th eir FCC catalyst inventory. Ni and V are of primary concern because of the ability of these metals to impair catalyst activity and to negatively impac t catalyst yields. Typical practices for higher metals operations have incl uded the use of equilibrium catalyst to "flush" contaminant metals from the unit, while adding minimal fresh catalyst just to maintain activity. This approach forces the unit to operate at a metal level that is often lower th an the optimum, to counteract the contaminant metals brought in with the eq uilibrium catalyst and the potential negative yields associated with them. Modem catalysts, which incorporate metal tolerant technologies that minimiz e the effects of Ni and V, can be used to improve the overall selectivity o f a particular unit's inventory. Fresh catalyst addition rates of these new technologies can often be much lower than the combined addition of "flushi ng" catalyst and fresh catalyst, with improvements in yields. This paper wi ll examine the differences between these methods of catalyst management.