V2O5-modified Mn-Ce/AC catalyst with high SO2 tolerance for low-temperature NH3-SCR of NO

Abstract

Development of the efficient catalysts with high SO2 tolerance for NH3-SCR is crucial to control NOx emission at low temperature. In this work, Mn-Ce/AC and Mn-Ce-V/AC catalysts were prepared through wet impregnations. The enhanced effects of V2O5 on the catalytic performance and SO2 tolerance over Mn-Ce/AC catalysts were evaluated in the temperature range of 100–300 °C. The denitration performance results indicated that doping V2O5 enhanced the NO conversion and N2 selectivity. Importantly, co-doping V2O5 made Mn-Ce(0.4)-V/AC exhibit improved SO2 tolerance than Mn-Ce/AC. The physical and chemical properties of fresh and SO2 poisoned catalysts were characterized by N2 physisorption, XRD, SEM-EDS, H2-TPR, NH3-TPD, SO2-TPD, XPS, and TG. The characterization results showed that doping V2O5 strengthened the surface acidity and enriched the surface chemisorbed oxygen resulting in accelerating the SCR reaction. The promoted SCR reaction and stronger surface acidity over Mn-Ce(0.4)-V/AC restrained the competitive adsorption of SO2 and limited the reaction between adsorbed SO2 and NH3 species. Moreover, the clusters of vanadium oxide species partly prevented the dispersive Mn-Ce solid solution from being sulfated by SO2. Finally, the probable mechanism for improved SO2 tolerance over V2O5-modified Mn-Ce(0.4)/AC catalyst was proposed.