Ceria-nano supported copper oxide catalysts for CO preferential oxidation: Importance of oxygen species and metal-support interaction

Abstract

CeO2 with four different morphologies (sphere, rod, octahedron, cube) are used as the supports to synthesize the CuCe catalysts for the CO preferential oxidation in the H2-rich gas and characterized by various techniques (TEM, HR-TEM, SEM, XRD, N2 physisorption, XPS, Raman spectra, CO-TPD, CO-DRIFTS, O2-TPD, CO pulses, H2-TPR) to obtain an insight into the impact of the CeO2 morphology on the surface structure, composition and redox properties, especially the active species. The four supports expose {111}, {110} and {100} planes, and sphere-shape CeO2 has a higher ratio of {111}, which can form more reductive copper species and active oxygen species. And the catalytic performance followed by this order: spheres (28.5 kJ/mol) > rods (31.0 kJ/mol) > octahedrons (34.1 kJ/mol) > cubes (40.3 kJ/mol). By further analysis of the characterization results, a series of structure-activity relationships are established to confirm that the active oxygen species is the decisive factor of preferential oxidation of CO in the H2-rich stream.