Comparative study of MCe0.75Zr0.25Oy (M = Cu, Mn, Fe) catalysts for selective reduction of NO by CO: Activity and reaction pathways

Basic oxygen furnace steelmaking leads to the production of CO-rich off-gas. When CO and NO are combined in off-gas, selective catalytic reduction by CO (CO-SCR) effectively achieves the synergistic removal of both pollutants. In this paper, CuCe0.75Zr0.25Oy, MnCe0.75Zr0.25Oy, and FeCe0.75Zr0.25Oy catalysts are prepared and evaluated for their CO-SCR activity, and the results show that the reaction system needs to be anaerobic; thus, the CO-SCR reaction can be dominant. The T90 values of CuCe0.75Zr0.25Oy and FeCe0.75Zr0.25Oy are 200 °C and 223 °C, respectively. The activities of these two catalysts are higher than that of MnCe0.75Zr0.25Oy (T90 = 375 °C). Linear nitrate and bridged bidentate nitrate are the main intermediate species involved in NO conversion on the catalyst surface, and bidentate CO32− coordination is the main intermediate species involved in CO conversion on the catalyst surface. CuCe0.75Zr0.25Oy has high lattice oxygen mobility and is more likely to react with NO and CO. In the presence of oxygen, most CO is oxidized by O2, which increases continuously to 100%, 100%, and 98% for CuCe0.75Zr0.25Oy, FeCe0.75Zr0.25Oy, and MnCe0.75Zr0.25Oy, respectively; additionally, CO is oxidized by O2, and the CO-SCR reaction cannot be carried out.