Revealing M (M = Mn, Fe, Co, Ti) oxides doping effects on NH₃-SCR coupled with CO oxidation mechanisms over CuO/CeO₂ catalyst under O₂-rich conditions

The simultaneous abatement of NO and CO from oxygen-rich flue gas remained a significant challenge. To address this, a series of M-doped (M = Mn, Co, Fe, Ti) CuO/CeO₂ catalysts was synthesized. Among them, the CuMnO_x/CeO₂ catalyst achieved 100% CO conversion at 150 °C, and 94.5% NO conversion at 200 °C. The results illustrated that the incorporation of Mn simultaneously enhanced both the surface acidity and redox properties of the CuO/CeO₂ catalyst, establishing a favorable balance between the two. In situ DRIFTS analysis unveiled that the NH₃-SCR process followed both E-R and L-H mechanisms, with Mn promoting the adsorption and activation of NH₃ and NO, which improved denitration efficiency. CO oxidation proceeded via M-v K and L-H pathways, where Mn doping increased the number of CO adsorption sites and active oxygen species, thus promoting the reaction. Additionally, competitive adsorption between NH₃ and CO was observed to reduce the synergistic activity. Mn doping provided additional adsorption and activation sites for NH₃, alleviating this inhibitory effect. This work offered a promising strategy for the simultaneous removal of NO and CO from oxygen-rich flue gases through NH₃-SCR coupled with CO oxidation on a single catalyst.