NO reduction with CO in the presence of O2 over Al2O3-supported and Cu-based catalysts

NO reduction with CO in the presence of O2 was examined over various kinds of Al2O3-supported and Cu-based catalysts. The effects of loaded elements, supports and calcination temperatures on catalysis for the NO–CO–O2 reaction system were investigated. We found that the most effective catalyst was 0.5 wt.% Cu/γ-Al2O3 calcined at 773 K. The states of Cu species were characterized with XRD, UV/VIS/NIR, EPR, TPR and X-ray absorption spectroscopic techniques. Highly dispersed Cu2+ species on Al2O3 are active species for selective reduction of NO to N2. The aggregated Cu species preferentially oxidize CO without reducing NOx, and the appearance of the aggregated Cu species resulted in drastic reduction in N2 formation capability.