Catalytic oxidation of biomass combustion emissions over K-M/MgO (M = Cu, Mn, Fe) mixed oxide catalysts

This study investigates the catalytic performance of a series of oxide catalysts for the combustion of a model gas mixture simulating emissions from biomass combustion. Low-cost raw materials were used to prepare monometallic catalysts (1%, 3%, and 5% K/MgO) and bimetallic catalysts (1%, 3%, and 5% K/(Cu/MgO), K/(Mn/MgO), and K/(Fe/MgO)). The model gas mixture consisted of CO, CH₄, C₁₀H₈, CO₂, air, and N₂. The catalysts were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermal analysis (DTA), nitrogen adsorption for BET surface area determination, and CO₂ temperature-programmed desorption (CO₂-TPD). The results demonstrate that all catalysts were active for the oxidation of CH₄ and C₁₀H₈, which those containing 1% potassium exhibiting the highest activity and achieving complete conversion at temperatures below 600 °C. Among the studied materials, the 1%K(5%Mn/MgO) catalyst showed the best performance, reaching 100% conversion of CH₄ and C₁₀H₈ at approximately 400 °C and 600 °C. The enhanced catalytic performance, particularly for the Mn-containing catalysts, is attributed to improved surface basicity and metal-support interactions at low potassium loadings, while higher K contents promote carbonate formation and surface area reduction, leading to partial deactivation.