In situ DRIFTS studies on CuO-Fe2O3 catalysts for low temperature selective catalytic oxidation of ammonia to nitrogen

Abstract

A series of CuO-Fe2O3 composite oxides were successfully prepared for low temperature selective catalytic oxidation of ammonia (NH3-SCO). Higher Cu/Fe ratio in CuO-Fe2O3 catalysts led to higher activity for NH3 oxidation and the lower Cu/Fe ratio improved the N2 selectivity. The optimal catalyst with a Cu/Fe molar ratio of 5:5 displayed a low complete conversion temperature (<250°C) with a relatively high N2 selectivity (>91%). H2-TPR results indicated that the synergistic effect existed between Fe2O3 and CuO, which was beneficial to the catalytic performance. The results of the DRIFTS showed that NH3-SCO reaction mainly followed the internal SCR (i-SCR) mechanism. The adsorbed NH3 was first activated and reacted with atomic oxygen to form the nitrosyl (-HNO). Then the -HNO was oxidized by oxygen atoms from O2 to form NO species. Meanwhile, the in situ-formed NO could react with -NH2 to form the main product of N2.