Study on the mechanism of NOx reduction by NH3-SCR over a ZnXCu1−XFe2O4 catalyst

Abstract

Experimental evidence shows that CuFe₂O₄ exhibits excellent catalytic performance in the SCR reaction. However, there is a lack of in-depth research on its specific reaction mechanism. Our study begins by computing the adsorption model of molecules like NH₃ and then goes on to examine the SCR reaction mechanism of NH₃ on CuFe₂O₄ before and after Zn doping. The results indicate that NH₃ is chemically adsorbed (−1.26 eV) on the surface and has a strong interaction with the substrate. Importantly, Zn doping provides more favorable reactive sites for NH₃ molecules. Subsequent investigation into the NH₃ dehydrogenation and SCR reaction processes showed that incorporating Zn can greatly decrease the energy barrier of the most critical step in the reaction (0.58 eV). Additionally, the study also assesses the feasibility of the reaction of adsorbed NO with surface active O atoms to form NO₂ (barrier 0.86 eV). Lastly, the sulfur resistance of the catalyst before and after doping is calculated and analyzed, and it is found that Zn doping effectively improves the sulfur resistance. Our study provides valuable theoretical guidance for the development of ferrite spinel and doping modification.