The nature of metal oxide on adsorptive and catalytic properties of Pd/MeOx/Al2O3 catalysts Original Research Article

The role of ceria, niobium and molybdenum oxides on the promotion of the NO reduction by CO was studied. A bifunctional mechanism was discussed as a function of both the nature of interaction between metal oxide and palladium and the redox properties of each metal oxide. The NO dissociation was better on the Pd/MoO3/Al2O3 catalyst than on the Pd/CeO2/Al2O3 and Pd/Nb2O5/Al2O3 catalysts. The explanation for the very high N2 production on Pd–Mo catalyst during the TPD analysis may be attributed to the NO+Meδ+ stoichiometric reaction. The promoting effect of a reducible oxide for the NO+CO reaction at low temperature can be ascribed mainly to its easiness for a redox interchange and its interaction with the noble metal particles. This would increase the surface redox ability and favor the dynamic equilibrium needed for high N2 selectivity.