Study On Denitrification Mechanism Of VWTI Catalyst Based On DFT

NO_x emissions in the atmosphere bring serious harm to the natural environment and human production and activities.Controlling NO_x emissions has been a hot topic at home and abroad.Selective catalyst reduction（SCR）technology is one of the main technologies for NO_x removal.The SCR catalyst is the core of this technology.The choice of catalyst directly affects the efficiency of SCR denitration.Based on the traditional research on vanadium-based SCR catalysts,this paper uses quantum chemistry-based density functional theory（DFT）to study the modification mechanism of vanadium-based catalysts,and discusses the scientific problem of SCR catalyst modification from a molecular level.The modification mechanism of vanadium-based SCR catalysts is described.Firstly,non-metallic F and N are used for doping the TiO₂ crystal of the V₂O₅/TiO₂catalyst with the metal sites Cu,La,and Ce at the O site of Ti.The different doping structure models are mainly constructed,and D,F,N,Cu,La,and Ce doped V₂O₅/TiO₂ catalyst structure bond length,NO adsorption energy,and state density,etc.The results show that the catalyst bond length changes after doping,which in turn causes minor changes in the catalyst structure;NO The calculation of the adsorption energy shows that the dopant energy of NO increases with the doping of Cu and Ce.The NO adsorption energy on the surface of Ce-V₂O₅/TiO₂ is the largest,which is-1.73 e V.State density analysis shows that the N,Cu,La,and Ce Doping makes the band gap of the catalyst structure smaller,the conduction band interval shifts to the left,and the valence band interval shifts to the electron conduction band interval,thereby improving the catalytic activity of the catalyst.Among them,the effect of Ce doping is obviously better than the doping of other elements,which is more beneficial to the catalytic reaction of SCR catalysts.A quantum-density-based density functional theory study of rare earth elements La,Ce,and Pr-doped V₂O₅-WO₃/TiO₂（001）catalysts was performed.By calculating the bond length,energy band,and partial density of states,It was found that the doping of the rare earth elements La,Ce and Pr had little effect on the structure of the V₂O₅-WO₃/TiO₂ catalyst,and the bond length did not change much;Ce-V₂O₅-WO₃/TiO₂ has the smallest band gap width of 0.08 e V,and electrons are more prone to transition;PDOS analysis shows that the doping of rare earth elements causes the CB interval of V₂O₅-WO₃/TiO₂ catalyst to move to the left,and the charge energy of CB interval decreases Smaller,easier to generate electronic transitions,thereby improving the catalytic activity of the catalyst surface.Furthermore,the adsorption reaction of NO and NH₃ on the surface of the catalyst Ce-V₂O₅/TiO₂（001）was further calculated by DFT.Adsorption behavior,analysis and calculation of the adsorption energy,geometric configuration parameters,charge,and partial state density of different adsorption sites,the results show that the adsorption of NO on the Ce-V₂O₅/TiO₂（001）surface is chemisorption,and The N-terminus is most stable when adsorbed at the top position,and the adsorption energy can reach-1.78 e V.The calculation results of the adsorption of NH₃ on the Lewis acid site and Br（?）nsted acid site on Ce-V₂O₅/TiO₂（001）surface show that the Br（?）nsted acid site has stronger adsorption on NH₃,with an adsorption energy of-2.95 e V.