Selective CO Oxidation in Excess H2 over Copper−Ceria Catalysts:  Identification of Active Entities/Species

Catalysts based on combinations between copper and cerium oxides are analyzed with respect to their catalytic properties for preferential oxidation of CO in a H2-rich stream (CO-PROX) by means of DRIFTS, XANES, and Raman under Operando conditions. The results allow analyzing entities/species responsible for the CO and H2 oxidation reactions taking place during the CO-PROX process. While CO oxidation takes place at copper oxide support interfacial sites and its activity correlates with the degree of reduction achieved on the dispersed copper oxide particles, H2 oxidation apparently proceeds when a massive copper oxide reduction occurs. This opens the possibility to modulate the catalytic behavior of these types of catalysts by acting, respectively, on the interfacial redox properties and on the dispersed copper oxide redox properties.