Mixed Oxides for Simultaneous CO and Toluene Catalytic Oxidation: Effect of Mn/Cu Ratio on Catalytic Performances

Manganese-copper (Mn-Cu) mixed oxides are promising catalysts for abatement of incomplete combustion products from domestic wood burning, notably CO and Volatile Organic Compounds (VOCs). In this paper, the influence of the Mn/Cu molar ratio on structure, redox properties, and catalytic performances was investigated. Mixed oxides were synthesized by oxalate co-precipitation and calcined under air at 500°C. Physicochemical characterization (XRD, Raman, N2-physisorption, XPS, H2-TPR) revealed strong Mn─Cu interaction. Catalytic tests for total oxidation of CO, toluene, and their mixture showed that copper-rich oxides, especially Cu1Mn0.25Ox, achieved the best performance at low temperature (T50 = 49°C and 230°C for the oxidation of CO and toluene respectively). In alternating feeding, the presence of CO promotes the oxidation of toluene at low temperature, while an excess of Cu in the material ensures full CO2 selectivity. For mixed oxides, the linear correlation between Cu2+ → Cu+ reducibility and T50 for toluene oxidation in presence of CO demonstrates that the incorporation of Mn into Cu oxides enhances oxidation. Overall, tuning the Mn/Cu ratio enables efficient, selective, and simultaneous removal of CO and VOCs, providing a cost-effective solution for emission control from biomass combustion.