Comparison of sulfur poisoning resistance of Ce/Mn doped γ-Fe2O3 (0 0 1) surface in NH3-SCR reaction with DFT method

Abstract

The catalyst is the core of the NH3-SCR NOx removal process, and sulfur resistance is important performance to ensure its stability and efficiency. The γ-Fe2O3 catalyst has great NOx removal efficiency but its sulfur resistance need to be enhanced to meet the needs of development of Fe based catalyst. In this paper, the sulfur resistance of γ-Fe2O3 and Ce/Mn doped catalyst was studied by quantum chemistry and DFT, and this study can reveal the adsorption process of sulfur oxides on the catalyst surface and the decomposition of surface sulfate. The result shows that the SO2 and SO3 prefer to be adsorbed on the Ce sites and let more Fe active sites exposed to participate NH3-SCR process, but the Mn doping hardly works on improving adsorption. Moreover, Ce doping can effectively decrease the activation energy of the decomposition of ammonium sulfate and promote its decomposition on the catalyst surface, but Mn doping almost cannot improve the decomposition of ammonium sulfate on the catalyst surface. Therefore, doping Ce on γ-Fe2O3 catalyst can effectively improve the sulfur resistance of the catalyst, while Mn has little effect.