Effects of MoO₃ and CeO₂ doping on the decomposition and reactivity of NH₄HSO₄ on V₂O₅/TiO₂ catalysts

The deposition of NH₄HSO₄ on catalysts is one of the key issues for selective catalytic reduction of NO_x. In this study, NH₄HSO₄ was preloaded on catalysts, and the effects of MoO₃ and CeO₂ doping on the decomposition and reactivity of NH₄HSO₄ on V₂O₅/TiO₂ catalysts are studied. The results show that the introduction of MoO₃ and CeO₂ significantly promoted NO_x conversion on the V₂O₅/TiO₂ catalysts. Doping with MoO₃ could effectively enhance the S and H₂O resistance of the catalysts. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis indicate that it is the strong chemical interactions between NH₄HSO₄ and the catalysts that are adverse to the decomposition of NH₄HSO₄. However, doping with MoO₃ apparently inhibits these interactions, which significantly decrease the decomposition temperature of NH₄HSO₄. In situ FTIR experiments show that the NH₄⁺ in preloaded NH₄HSO₄ could react with gaseous NO on catalysts, and doping with MoO₃ could facilitate the reaction rate.