New models of catalyst deactivation by coke: II. Coking of supported platinum catalysts

Metal and support deactivation upon the coking of supported metal catalysts occurs via different mechanisms. Several models of coking are presented. The most complete complex model is developed for supported platinum catalysts. It implies multilayer coke formation on support, the rapid formation of polymeric coke capable of self-regeneration by hydrogen directly in the course of reaction on platinum, and the slow conversion of this coke into graphite-like coke, which is removed only by oxidative regeneration. The models are experimentally supported for cyclohexane dehydrogenation.