Investigation of the initial rapid deactivation of platinum catalysts during the selective oxidation of carbon monoxide

This paper reports on a study using isotopic transient kinetics analysis (ITKA) to understand the initial rapid deactivation behavior of a 5 wt% Pt/γ-Al2O3 catalyst during selective CO oxidation in hydrogen. The Pt catalyst exhibited the rapid deactivation typically seen for such catalysts during the initial reaction period. Based on ITKA results, the pseudo-first-order intrinsic rate constant was found to be relatively constant with time on stream while the concentration of surface intermediates leading to CO2 decreased significantly. It can be concluded that the deactivation of this Pt catalyst is mainly the result of a decrease in the concentration of surface intermediates as a result of carbon deposition, not a change in the intrinsic site activity.