INVESTIGATION OF THE KINETICS OF A DEACTIVATING SYSTEM BY TRANSIENT EXPERIMENTS

A transient approach has been applied to a system deactivating due to coke formation, in order to determine the kinetics for the main reacti on. The method, which was used on a Pt-Sn/Al2O3 catalyst deactivated d uring propane dehydrogenation, consisted of runs in which the gas comp osition and temperature were changed in steps. By separating the deact ivation from the main reaction kinetics, it was possible to obtain rat e equations. A simple power-law model was found to fit the data best. Finally, simulations using the model for the main reaction together wi th a model for the deactivation mechanism were successfully applied to original data. The paper also discusses problems with non-uniform cok e profiles in integral reactors, and errors induced in kinetic paramet ers by using methods that utilize extrapolation to zero process time w hen finding mechanistic models. (C) 1998 Elsevier Science B.V.