Effect of Indium Addition on the Low-Temperature Selective Catalytic Reduction of NO(x) by NH(3) over MnCeO(x) Catalysts: The Promotion Effect and Mechanism

[Image: see text] A MnCeInO(x) catalyst was prepared by a coprecipitation method for denitrification of NH(3)-SCR (selective catalytic reduction). The catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller analysis, H(2) temperature-programmed reduction, and NH(3) temperature-programmed desorption. The NH(3)-SCR activity and H(2)O and SO(2) resistance of the catalysts were evaluated. The test results showed that the SCR and water resistance and sulfur resistance were good in the range of 125–225 °C. The calcination temperature of the Mn(6)Ce(0.3)In(0.7)O(x) catalyst preparation was studied. The crystallization of the Mn(6)Ce(0.3)In(0.7)O(x) catalyst was poor when calcined at 300 °C; however, the crystallization is excessive at a 500 °C calcination temperature. The influence of space velocity on the performance of the catalyst is great at 100–225 °C. FTIR test results showed that indium distribution on the surface of the catalyst reduced the content of sulfate on the surface, protected the acidic site of MnCe, and improved the sulfur resistance of the catalyst. The excellent performance of the Mn(6)Ce(0.3)In(0.7)O(x) catalyst may be due to its high content of Mn(4+), surface adsorbed oxygen species, high specific surface area, redox sites and acid sites on the surface, high turnover frequency, and low apparent activation energy.