DEACTIVATION OF THE CATALYST PT-SN/AL2O3 DURING DEHYDROGENATION OF METHYLCYCLOHEXANE

A modified Pt-Sn/Al2O3 industrial catalyst was used to study the dehydrogenation of methylcyclohexane. Despite this modification, the catalyst deactivates during the reaction. The deactivation is the result of a coke deposit on the catalyst surface. This deposit constitutes two kinds of poisons: one reversible, the other irreversible. A reaction mechanism is proposed which takes into account the deactivation, and a kinetic model of deactivation is developed. Using experimental data obtained in a Berty reactor, the constants for the deactivation model were calculated by the least squares method coupled with the simplex method. The model was tested by comparing the calculated conversions with experimental conversions obtained in a Berty reactor and in a plug flow reactor. Finally, a parametrical analysis was conducted using the model. The simulated effects of temperature and hydrogen flow were outlined. By choosing judiciously the operating conditions and the type of reactor, the deactivation can theoretically be avoided.