Kinetic study of propane dehydrogenation and side reactions over Pt-Sn/Al2O3 catalyst

The kinetics of reactions involved in dehydrogenation of propane to propylene over Pt-Sn/Al2O3 catalyst was studied. The simultaneous deactivation of individual dehydrogenation, hydrogenolysis and cracking sites was also studied. A model was developed to obtain the transient conversion of propane, product selectivity and catalytic site activity. The dehydrogenation reaction was considered as the main reaction governing propane and hydrogen concentrations along the reactor. Catalytic test runs were performed in a fixed-bed quartz reactor. The kinetic expressions developed for the main and side reactions were verified by integral and a combination of integral-differential analysis of reactor data, respectively, and the kinetic parameters were obtained. The deactivation of the active sites for the three reactions was found to follow a first-order independent decay law. The rate constants of deactivation were found to decrease in the order of dehydrogenation, hydrogenolysis and cracking. Noncatalytic thermal cracking was found to be comparable to the catalytic route resulting in a very low apparent deactivation rate constant for cracking reaction. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.