Effect of Tourmaline Addition on the Catalytic Performance and SO 2 Resistance of Ni x Mn 3−x O 4 Catalyst for NH 3 -SCR Reaction at Low Temperature

NixMn3−xO4 and NixMn3−xO4/T (T represents tourmaline) catalysts with a double-layer hollow structure were prepared by a rigid template method for low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR). The catalytic activity and SO2 tolerance performance of NixMn3−xO4 catalyst were enhanced by the addition of 2 wt% tourmaline. The results showed the addition of tourmaline could affect the growth, shell thickness and redox property of the NixMn3−xO4 catalysts. The relative contents of Mn4+ and surface chemical oxygen were also increased by the addition of tourmaline, which were beneficial for improving the SCR activity, the catalyst showed 100% NO conversion in a low-temperature range of 125–240 °C. The mechanism of SCR reaction and SO2 tolerance were analyzed by In-situ DRIFTS. The SCR reaction process mostly follows Langmuir–Hinshelwood (L–H) mechanisms. The primary NOx adsorption materials on NixMn3−xO4/T catalyst were nitrate bidentate and bridge nitrate, which was not affected by SO2, and it had excellent SO2 tolerance at 150 ℃.