Modeling of kinetics and deactivation in the direct epoxidation of propene over gold-titania catalysts

A reaction model was developed for the epoxidation of propene oxide over gold-titania catalysts. This model involves the formation of a bidentate propoxy species on titania after the adsorption of propene, which is activated by gold. Aided by a peroxide species produced from hydrogen and oxygen on a gold nanoparticle, this species can reactively desorb from the catalyst to produce propene oxide. A reversible catalyst deactivation occurs by a consecutive oxidation of the bidentate propoxy species to carbonate species. The kinetic model is able to give a good description of the experimentally observed catalytic performance in the low-temperature range (up to 365 K), where the selectivity of the catalyst is high.