Experimental investigation on the decomposition of NH4HSO4 over V2O5-WO3/TiO2 catalyst by NH4NO3 at low temperature

[Display omitted] •Adding NH4NO3 broadened the operating temperature range of VWTi catalyst.•The SCR activity of VWTi catalyst was improved at low temperature using NH4NO3.•The SO2 tolerance of catalyst was increased by using NH4NO3.•The addition of NH4NO3 accelerated the decomposition of NH4HSO4. Deactivation by NH4HSO4 deposition is one of the major problems faced by commercial SCR catalysts at low temperatures. In this study, NH4NO3 was added to the SCR reaction atmosphere in the presence of H2O and SO2 at 250 °C, which is lower than the typical temperatures suitable for the V2O5-WO3/TiO2 catalyst. After a long test, the catalyst activity decreased from 82 % to 75 %, which is much smaller than the activity drop in the atmosphere without NH4NO3. The characterization results indicate that the addition of NH4NO3 effectively reduced the deposition of NH4HSO4 on the catalyst surface, thus weakening the degree of catalyst poisoning deactivation. In addition, we examined the effect of NH4NO3 addition on the regeneration of catalysts deactivated by NH4HSO4. The activity of the catalyst deactivated by 5 wt% NH4HSO4 recovered efficiently after the deactivated catalyst was treated by NH4NO3, NO and O2 for 1 h at 250 °C. The SEM, FTIR, and BET characterization results reveal the positive effect of NH4NO3 in promoting the decomposition of NH4HSO4.