Role of the Cu content and Ce activating effect on catalytic performance of Cu-Mg-Al and Ce/Cu-Mg-Al oxides in ammonia selective catalytic oxidation

Abstract

Copper-containing mixed metal oxides were studied as catalysts for selective catalytic oxidation of ammonia. The performed research shows a high correlation between Cu amount and catalyst efficiency, especially dinitrogen selectivity. Copper species, mainly in the form of highly dispersed CuO oxides, were found to be responsible for high N2 selectivity, which decreased with increasing Cu loading and the formation of CuO bulk-like species. The addition of cerium seemed to have an effect on material’s catalytic activity and N2 selectivity. The increase in selectivity towards N2 of Ce-impregnated materials was attributed to the formation of copper-cerium redox couples on the material’s surface. The catalytic tests performed under different NH3/O2 molar ratios revealed that the developed materials exhibit high catalytic activity in a wide range of ammonia concentrations and oxygen contents.