Operando DRIFTS and XANES Study of Deactivating Effect of CO₂on a Ce0.8Cu0.2O₂CO-PROX Catalyst

Deactivating effects produced by CO 2 on a catalyst combining oxidized copper and cerium prepared by microemulsion−coprecipitation and employed for preferential oxidation of CO in a H 2 -rich stream have been examined by means of operando-DRIFTS and -XANES (Cu K and Ce L 3 edges) spectroscopies. The results reveal that CO oxidation activity is basically affected by CO 2 -induced hindrance of redox activity at the interface between dispersed copper oxide particles and the support as a consequence of carbonate formation. This appears influenced by support acid−base properties, as revealed by comparison of the obtained results with those observed over a different catalyst that was prepared by copper impregnation on pure ceria. CO 2 is shown to affect negatively H 2 oxidation activity, too, which is related to prevention of the extension of the reduction from the interface to the rest of the dispersed copper oxide particles, a process that provides active sites for such reaction.