Activation of NH3 at Nickel-Induced Lewis Acid Sites over CeVO4 Catalysts for the Selective Catalytic Reduction Nitric Oxide

This study employs density functional theory (DFT) to investigate the reaction mechanisms of NH3 selective catalytic reduction of NO on Ni-doped CeVO4 (200) surfaces, as well as the mechanism of sulfur poisoning, to understand the impact of Ni doping on the catalytic performance and sulfur resistance of CeVO4 catalysts. We systematically examined the NH3-SCR mechanism on NiCeVO4, including two consecutive NO reduction pathways. Simulations of the adsorption/dissociation behavior of NH3, O2, and NO molecules on the catalyst, both before and after doping were conducted. The results indicate that Ni doping significantly alters the electronic charge properties of the CeVO4 surface, markedly improving the adsorption characteristics of gas molecules and considerably lowering the dissociation energy barrier. In both CeVO4 and Ni-CeVO4 catalyst systems, the reaction follows the Eley-Rideal mechanism. The Ni doping reduces the activation barriers for the formation of intermediates NH2 and NH2NO, with NH2 formation identified as the rate-determining step. Additionally, the adsorption of SO2 and H2O and the dissociation pathways of ammonium sulfate before and after doping were studied. It was found that Ni doping considerably reduces the adsorption of H2O and SO2 and lowers the dissociation barrier of ammonium sulfate, thereby enhancing the catalyst’s water and sulfur resistance.