Pt-Mo bimetallic catalysts supported on Y-zeolite: II. Activity and selectivity in n-butane conversion

Pt-Mo bimetallic catalysts prepared by adsorption and decomposition of Mo(CO)6 on 1-nm Pt aggregates supported on Y-zeolite exhibit enhanced hydrogenolysis activity with respect to PtY zeolite in n-butane conversion. The activity curve vs PtMo composition is volcano-shaped with a maximum near equiatomic composition. The rate at maximum is 7 and 34 times larger than on PtNaHY and PtSiO2, respectively. The reaction orders with respect to n-C4 and H2 are positive in a large range of pressures. The kinetic parameters are interpreted in terms of the participation of both Pt and Mo atoms in the reaction mechanism. Mo atoms act primarily as strong adsorption sites for the hydrocarbon whereas hydrogen atoms dissociated on Pt are required to hydrogenate the hydrocarbon fragments.