Enhancement low-temperature NH3-SCR activity of the Fe-Mn-Mo/TiO2 catalyst and its DFT calculations and kinetics

The 5 %Fe-3 %Mn-3 %Mo/TiO2 catalyst was prepared by impregnation method, and the effects of Mn, Mo doping on the structure and NH3-SCR performance of Fe-based catalysts were investigated. The 5 %Fe-3 %Mn-3 %Mo/TiO2 catalyst showed highest NH3-SCR activity (over 80 % NO conversion at 200–400 °C) and best long-time stability. Especially, the conversion rate of NO was 97 % at 250–300 °C. The introduction of Mn, Mo increased the surface acidity and redox ability of the 5 %Fe/TiO2 catalyst and improved the dispersion of active components (Fe). DFT calculations showed that the Mo-MnFe2O4 (311) surface over 5 %Fe-3 %Mn-3 %Mo/TiO2 catalyst had the strongest adsorption capacity for NO and NH3, which was more favorable for the SCR process, and this result was consistent with the NH3-SCR activity test. Kinetics results indicated the apparent activation energy of the 5 %Fe-3 %Mn-3 %Mo/TiO2 catalyst decreased by 39 % when compared to 5 %Fe/TiO2. It was evident that the addition of Mn and Mo reduced the apparent activation energy of the catalyst.