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[Display omitted] • Adding NH 4 NO 3 broadened the operating temperature range of VWTi catalyst. • The SCR activity of VWTi catalyst was improved at low temperature using NH 4 NO 3. • The SO 2 tolerance of catalyst was increased by using NH 4 NO 3. • The addition of NH 4 NO 3 accelerated the decomposition of NH 4 HSO 4. Deactivation by NH 4 HSO 4 deposition is one of the major problems faced by commercial SCR catalysts at low temperatures. In this study, NH 4 NO 3 was added to the SCR reaction atmosphere in the presence of H 2 O and SO 2 at 250 °C, which is lower than the typical temperatures suitable for the V 2 O 5 -WO 3 /TiO 2 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 NH 4 NO 3. The characterization results indicate that the addition of NH 4 NO 3 effectively reduced the deposition of NH 4 HSO 4 on the catalyst surface, thus weakening the degree of catalyst poisoning deactivation. In addition, we examined the effect of NH 4 NO 3 addition on the regeneration of catalysts deactivated by NH 4 HSO 4. The activity of the catalyst deactivated by 5 wt% NH 4 HSO 4 recovered efficiently after the deactivated catalyst was treated by NH 4 NO 3 , NO and O 2 for 1 h at 250 °C. The SEM, FTIR, and BET characterization results reveal the positive effect of NH 4 NO 3 in promoting the decomposition of NH 4 HSO 4. [ABSTRACT FROM AUTHOR]