Unlocking the Potential of Metal-Doping Fe₂O₃/Rice Husk Ash Catalysts for Low-Temperature CO-SCR Enhancement

Transition metal oxides are efficient bifunctional catalysts for the selective catalytic reduction (SCR) of nitrogen oxides (NO) using CO. Nonetheless, their poor activity at lower temperatures constrains broader industrial application. Herein, we propose an optimized Fe₂O₃-based catalyst through strategic metal doping with Cu, Co, or Ce, which engenders a harmonious balance for the synergistic removal of CO and NO. Among the developed catalysts, Co-doped Fe₂O₃, supported by rice husk ash, demonstrates superior low-temperature CO-SCR activity, achieving CO and NO conversion ratios and N₂ selectivity above 98.5% at 100-500 °C. The enhanced catalytic performance is attributed to the catalyst's improved redox properties and acidity, engendered by strong Fe-O-Co interactions. Furthermore, the CO-SCR reaction adheres to the Langmuir-Hinshelwood and Eley-Rideal mechanisms. Our findings shed light on the future industrial application of low-temperature CO and NO near-zero emission technology and provide a strategy for the design of low-cost SCR catalysts.