Comparative study of MCe_0.75Zr_0.25O_y (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, CuCe _0.75Zr _0.25O _y, MnCe _0.75Zr _0.25O _y, and FeCe _0.75Zr _0.25O _y 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 T ₉₀ values of CuCe _0.75Zr _0.25O _y and FeCe _0.75Zr _0.25O _y are 200 °C and 223 °C, respectively. The activities of these two catalysts are higher than that of MnCe _0.75Zr _0.25O _y (T ₉₀ = 375 °C). Linear nitrate and bridged bidentate nitrate are the main intermediate species involved in NO conversion on the catalyst surface, and bidentate CO ₃ ²⁻ coordination is the main intermediate species involved in CO conversion on the catalyst surface. CuCe _0.75Zr _0.25O _y 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 O ₂, which increases continuously to 100%, 100%, and 98% for CuCe _0.75Zr _0.25O _y, FeCe _0.75Zr _0.25O _y, and MnCe _0.75Zr _0.25O _y, respectively; additionally, CO is oxidized by O ₂, and the CO-SCR reaction cannot be carried out.