H-2 purification through preferential oxidation of CO over ceria supported bimetallic Au-based catalysts

CeO2 supported mono and bimetallic Au catalysts (AuAg, AuCu, AuPd, AuRu), prepared by deposition-precipitation, were tested in the preferential oxidation of CO in the excess of H2 (PROX). Activity data showed that the PROX performances of Au/CeO2 are boosted by addition of Ag and to a minor extent Cu, whereas Ru and Pd have a negative effect. For both AuAg and AuCu systems the deposition order did not affect the catalytic performance whereas 1wt%/1wt% was found as the optimal Au/second metal ratio. On the basis of characterization data (H2-TPR, TG-DTA, DRIFT, Surface Area measurements) it was proposed that the addition of Ag and Cu to Au/CeO2 leads to a higher reactivity of surface ceria oxygen involved in the PROX reaction through a Mars-van Krevelen mechanism. The higher activity of the AuAg/CeO2 system was attributed to the occurrence of a strong mutual interaction between gold and silver that positively affects the PROX performance in terms of yields to CO2 and stability under reaction conditions.