Insights into the highly activity CuMgFe oxides for the selective catalytic reduction of NO by CO: Structure-activity relationships and K/SO2 poisoning mechanism

Abstract

The selective catalytic reduction of NO by CO is a promising technology for the simultaneous removal of both NO and CO pollution. Hence, a series of CuMgFe composite metal oxides with flower-like morphology was prepared by co-precipitation method for SCR of NO by CO. CuMgFe oxide calcined at 500 °C (CuMgFe-500) exhibited excellent low temperature activity. NO conversion reaches 100% at 225 °C, and it exhibits superior anti-H2O/SO2 ability (250 °C). The excellent activity of CuMgFe-500 was associated with its abundance of surface oxygen vacancies and excellent redox performance. The reaction mechanism of CuMgFe-500 CO catalytic reduction of NO was investigated by in situ DRIFTS. The results show that monodentate nitrate and labile carbonate intermediate species are generated on the catalyst surface. Its reaction follows the E-R mechanism and the L-H mechanism. The introduction of K reduced the surface oxygen adsorption and redox properties of CuMgFe-500 catalyst, which were the main reason for the poor low-temperature activity of K-poisoned catalyst. In situ DRIFTS analysis showed that SO2 hardly inhibits NO adsorption, which were the main reason for the excellent sulfur resistance of CuMgFe-500. This work provides new insights into the development and design of low-temperature CO-SCR catalysts.