Promoting effect of Zr on the catalytic combustion of methane over Pd/γ-Al2O3 catalyst

The effect of Zr on the catalytic performance of Pd/gamma-Al2O3 for the methane combustion was investigated. The results show that the addition of Zr can improve the activity and stability of Pd/gamma-Al2O3 catalyst, which, based on the catalyst characterization (N-2 adsorption, XRD, CO-Chemisorption, XPS, CH4-TPR and O-2-TPO), is ascribed to the interaction between Pd and Zr. The active phase of methane combustion over supported palladium catalyst is the Pd-0/Pd2+ mixture. Zr addition inhibits Pd aggregation and enhances the redox properties of active phase Pd-0/Pd2+. H-2 reduction could effectively reduce the oxidation degree of Pd species and regenerate the active sites (Pd-0/Pd2+).