Fluid catalytic cracking (FCC): activity in the (milli)seconds range in an entrained flow reactor

The kinetic model of catalytic cracking of a hydrowax feedstock has been studied using a bench-scale entrained flow reactor. It is shown that coke is deposited on the catalyst within the first 50 ms, probably at the first contact of feedstock and catalyst from non-selective initial cracking of the feedstock. In these initial reactions, the gasoline selectivity is low in favor of a higher gas production. After this initial conversion, the reactions taking place can be described by first-order reaction kinetics with a constant catalyst activity as a function of residence time. When a catalyst is used in a second run without regeneration, the activity is still significant, although much lower than that after regeneration. The overall selectivity of the reused catalyst is almost identical to the overall selectivity of the regenerated catalyst. The initial coke deposition found is so fast that it is strongly governed by internal diffusion limitations resulting in an egg-shell deposition on the catalyst matrix. (C) 1999 Elsevier Science B.V. All rights reserved.