Enhanced SO2 tolerance of V2O5-Sb2O3/TiO2 catalyst for NO reduction with co-use of ammonia and liquid ammonium nitrate

This study has examined the suppression of ammonium bisulfate (NH4HSO4, ABS) formation by SO2 and the active site recovery of the catalyst deactivated by ABS as well as catalytic performance enhancement at low temperatures by simultaneously injecting liquid ammonium nitrate (NH4NO3, AN) in ammonia-selective catalytic reduction (NH3-SCR) of NOx over V2O5-Sb2O3/TiO2 (V-Sb/Ti) catalyst. The SCR reaction involving co-injection of NH3 and AN showed an improvement in catalytic performance of at least 40% at 250 °C; compared to injection of NH3 only, the simultaneous injection of NH3/AN significantly decreased catalytic deactivation by SO2, which causes a critical problem in low-temperature NH3-SCR. To study the effects of co-injection of NH3/AN in the NH3-SCR, catalytic properties of fresh, spent, and ABS deposited catalysts were analyzed using various methods such as FT-IR, XRD, XPS, and EDS. A comparative analysis between the reaction results and catalyst characterizations revealed that the co-injection of NH3/AN induces the effect of Fast-SCR, and its effect restores the active sites deactivated by ABS as well as suppresses ABS formation on the catalyst surface during the SCR reaction with SO2, thereby enhancing catalytic performance and reducing catalytic deactivation at low temperatures.