Effects of SO2 and H2O on low-temperature NO conversion over F-V2O5-WO3/TiO2 catalysts.

F-V2O5-WO3/TiO2 catalysts were prepared by the impregnation method. As the content of F ions increased from 0.00 to 0.35 wt.%, the NO conversion of F-V2O5-WO3/TiO2 catalysts initially increased and then decreased. The 0.2F-V2O5-WO3/TiO2 catalyst (0.2 wt.% F ion) exhibited the best denitration (De-NOx) performance, with more than 95% NO conversion in the temperature range 160-360°C, and 99.0% N2 selectivity between 110 and 280°C. The addition of an appropriate amount of F ions eroded the surface morphology of the catalyst and reduced its grain size, thus enhancing the NO conversion at low temperature as well as the sulfur and water resistance of the V2O5-WO3/TiO2 catalyst. After selective catalytic reduction (SCR) reaction in a gas flow containing SO2 and H2O, the number of NH3 adsorption sites, active component content, specific surface area and pore volume decreased to different degrees. Ammonium sulfate species deposited on the catalyst surface, which blocked part of the active sites and reduced the NO conversion performance of the catalyst. On-line thermal regeneration could not completely recover the catalyst activity, although it prolonged the cumulative life of the catalyst. In addition, a mechanism for the effects of SO2 and H2O on catalyst NO conversion was proposed.