Superior resistance to alkali metal potassium of vanadium-based NH3-SCR catalyst promoted by the solid superacid SO42−-TiO2

Abstract

The significant decrease of acid sites caused by alkali metal poisoning is the major factor in the deactivation of commercial V2O5-WO3/TiO2 NH3-SCR catalysts. In this work, the solid superacid SO42−-TiO2 modified by sulfate radicals, was selected as the catalyst support, which showed superior potassium resistance. The physicochemical properties and K-poisoning resistance of the V2O5-WO3/SO42−-TiO2 (VWSTi) catalyst were carried out by XRD, BET, H2-TPR, NH3-TPD, XPS, in situ DRIFTS and TG. The results pointed out that the introduction of SO42− significantly increased the NH3-SCR catalytic activity at high temperatures, with an exceptionally high NOx conversion over 90% between 275 °C and 500 °C. When 0.5% (mass) K2O was doped on the catalysts, the catalytic performance of the traditional V2O5-WO3/TiO2 (VWTi) catalyst decreased significantly, while the VWSTi catalyst could still maintain a NOx conversion over 90% in the range of 300–500 °C. The characterizations suggested that the support of SO42−-TiO2 greatly increased the number of acidic sites, thereby enhancing the adsorption capacity of the reactant NH3. The results above demonstrated a potential approach to achieve superior potassium resistance for NH3-SCR catalysts using solid superacid.