NO reduction with CO in the presence of O 2 was examined over various kinds of Al 2 O 3 -supported and Cubased catalysts. The effects of loaded elements, supports and calcination temperatures on catalysis for the NO-CO-O 2 reaction system were investigated. We found that the most effective catalyst was 0.5 wt.% Cu/g-Al 2 O 3 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 Cu 2+ species on Al 2 O 3 are active species for selective reduction of NO to N 2 . The aggregated Cu species preferentially oxidize CO without reducing NO x , and the appearance of the aggregated Cu species resulted in drastic reduction in N 2 formation capability.
The V 2 O 5 catalysts supported on TiO 2 -SiO 2 -MoO 3 (TSM) prepared by the coprecipitation method were investigated for the selective catalytic reduction (SCR) of NO by NH 3 at low temperatures. The V 2 O 5 /TSM catalyst with 7-13 wt% SiO 2 was found to exhibit a superior SCR activity and a good sulfur tolerance at low temperatures (<250°C). The presence of highly active polymeric vanadates formed by the incorporation of MoO 3 to TiO 2 -SiO 2 and superior redox properties seems to enhance SCR activity, and furthermore the very lower SO 2 oxidation activity due to the higher acidity leads to the remarkable improvement of sulfur tolerance.
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