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_x) 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_x. Among the developed catalysts, Co-doped Fe₂O₃, supported by rice husk ash, demonstrates superior low-temperature CO-SCR activity, achieving CO and NO_x 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_x-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_x near-zero emission technology and provide a strategy for the design of low-cost SCR catalysts.