Investigation of the promotion effect of WO3 on the decomposition and reactivity of NH4HSO4 with NO on V2O5-WO3/TiO2 SCR catalysts

In this study, we systematically investigated the interaction between NH4HSO4 and WO3-promoted V2O5/TiO2 catalysts in the selective catalytic reduction of NO with NH3, along with the promotion effect of WO3 on the decomposition and reactivity of NH4HSO4 with NO. In the NH4HSO4-deposited samples, WO3 addition increased the electron cloud density around the S atoms in SO42-, which was beneficial for the reduction of S atoms with +6 formal oxidation number, as in NH4HSO4, to those in the +4 oxidation state, as in SO2. Consequently, WO3-doping led to an increase in the amount of SO2 released at low-temperature regions during the heating process as well as an obvious enhancement in the decomposition behavior of NH4HSO4, as illustrated by decreases in temperatures attributed to the weight loss peaks. Meanwhile, the introduced WO3 had a slight promotion effect on the reactivity of NH4HSO4 with NO, together with an inhibitory effect on the production of N2O during the reaction process. Finally, WO3-promoted catalysts exhibited enhanced SO2-resistance.