Methanol decomposition over bimetallic Cu-M catalysts supported on nanoceria: Effect of the second metal on the catalytic properties

Bimetallic Cu-M/CeO2 catalysts (M = Ni, Pd or Pt) with total metal content of 5 wt. % were synthetized by wet co-impregnation over CeO2. Three Cu/M atomic compositions, in each case, copper being the most abundant metal, were addressed. Materials were characterized by N-2 Adsorption, EDS, XRD, Raman spectroscopy, H-2 TPR, N2O chemisorption, CO-DRIFTS and catalytic properties were studied in the methanol decomposition reaction. Addition of a second metal to the Cu/CeO2 influences the dispersion of the active phases, as well as the reduction properties of the catalysts. Through a DRIFTS study of CO adsorbed on the surface of the bimetallic Cu-M/CeO2 catalysts, identification of the mixing pattern on the ceria surface is proposed: Cu-Ni nanoparticles in close contact (heterodimers), Cu-Pd mixed alloys and Cu-Pt core-shell structures. In general, addition of the second metal to copper-ceria catalyst boosts the catalytic activity, no matter the metal, while the hydrogen selectivity is also improved. Stability tests showed differences depending on the nature of the second metal. Deactivation issues are partially related to the blocking of active sites by carbonaceous species.