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

Development of the efficient catalysts with high SO₂ tolerance for NH₃-SCR is crucial to control NO_x 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.