Influence of calcination temperature on SO2 resistance of Mn‐Fe‐Sn/TiO2 catalysts at low‐temperature

Abstract

AbstractThe Mn‐Fe‐Sn/TiO2(MFST) catalysts for NO and Hg co‐removal with SO2 resistance at low temperature were prepared by the impregnation method under different calcination temperatures (300, 400, 500, and 600°C). The influences of calcination temperatures on SO2 resistance and of SO2 concentration on both denitration and demercuration performances of the Mn‐Fe‐Sn/TiO2 catalysts were investigated in a fixed‐bed reaction system. Surface physicochemical characteristics and SO2 resistance mechanism of MFST catalysts were analyzed by means of Brunauer–Emmett–Teller (BET), X‐ray diffraction (XRD), H2‐temperature‐programmed reduction (H2‐TPR), and X‐ray photoelectron spectroscopy (XPS). The results showed that the NO and Hg0 removal efficiency of the MFST catalysts was not affected by reaction temperature between 200–280°C in the absence of SO2. However, the NO and Hg0 removal efficiency was affected mostly in SO2‐containing atmosphere. Appropriate calcination temperature can alleviate SO2 poisoning and improve catalytic activity. When the calcination temperature was below 500°C, MFST catalysts have good resistance to the SO2, and it was found that at calcination temperature of 400°C, the NO and Hg0 removal efficiency had the minimum decay from 95% to 70% and 99% to 93% at 700 ppm SO2, respectively, which was higher than that of other catalysts. That was mainly due to the abundant BET surface area and pore parameters and the high ratio of Mn4+/(Mn4+ + Mn3+), Fe3+/(Fe3+ + Fe2+), and Oα/(Oα + Oβ) on catalyst surface. At lower calcination temperature (≤400°C), the metal active ingredient did not calcined sufficiently that made the NO and Hg0 removal efficiency declined. While at higher calcination temperature (>400°C), the catalyst tended to agglomeration and MnO2 was converted into Mn2O3 gradually. Furthermore, doping Fe and Sn can effectively reduce the consumption of Mn4+, which greatly improved the catalytic activity and the SO2 resistance.