Study on the mechanism of NOx reduction by NH3-SCR over Mn and M(M=V,Ti) co-doped CoCr2O4 catalyst

Abstract

Being based on the first-principles calculation method of density functional theory, our work calculated the optimized configuration of CoCr2O4(100) before and after co-doping of Mn and V(Ti). The adsorption behaviors of NH3, NO, NO2 and other gas molecules on the catalyst before and after doping were simulated. The optimized structures and related energy distribution of NH3 dehydrogenation reaction and SCR reaction on Mn0.1Co0.9V0.1Cr1.9O4 and Mn0.1Co0.9Ti0.1Cr1.9O4 catalysts were also fully studied. Our results reveal that the co-doping of heteroatom towards CoCr2O4(100) may result in electron migration and lattice dislocations as well as improving the surface acid activity. Therefore, the co-doping of Mn and V or Mn and Ti are believed to improve the adsorption of NH3, NO, NO2 and other gas molecules on the CoCr2O4 catalyst and significantly reduce the activation energy barrier of the NH3 dehydrogenation reaction and the SCR reaction. Furthermore, we studied the adsorption of SO2 and H2O on the co-doped catalyst, which exhibited that the co-doping of Mn and Ti may effectively improve the water and sulfur resistance of the catalyst. Our research are expected to be full of important theoretical guiding significance for the development, preparation and modification of cobalt-chromium spinel catalysts.