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 NOx. 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 NOx 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.