Catalytic Reductions of NO with H2, CO or NH3 over Supported Metal Oxide Catalysts

The roles of reducing agents such as H2, CO and NH3 in catalytic reduction of NO over supported metal oxide catalysts were studied from the viewpoint of reaction mechanisms. The reaction of NO with H2 or CO was proved to proceed through the redox cycles of the catalyst, that is, catalyst was oxidized by NO and then was reduced, to complete the catalytic sequence by the reducing agents. On the other hand, it was confirmed that NH3 or fragments of NH3 directly reacted with the adsorbed NO.These differences of the roles of reducing agents in the reaction mechanism satisfactorily explain some features of catalytic removal of NO in the practical process containing oxygen.