Effect Of Support Modification On Denitrification Performance Of Vanadium Titanium SCR Catalyst

SCR technology is the most widely used in denitration technology.The core of the system is catalyst.The performance of the catalyst directly affects the denitration efficiency of the entire SCR system.Therefore,the study of catalysts with high activity temperature window and high activity of NH₃-SCR has important practical significance for the removal of nitrogen oxides from coal-fired power plants.In this paper,the modification of traditional V₂O₅/TiO₂ catalysts was carried out.S?N non-metal elements and Nd rare earth metals were selected as TiO₂ doping sources to improve the SCR activity and sulfur and water resistance of V₂O₅/TiO₂catalysts in low temperature range.In order to further analyze the reasons why doping affects the activity of the catalyst,various characterization methods were used,such asN₂ adsorption and desorption and BET calculation methods,X-ray diffraction?XRD?technology,Raman technique,temperature programmed desorption?NH₃-TPD?,H₂-procedure.The specific research contents are as follows:Firstly,non-metal S and N co-doped TiO₂ carriers were prepared by sol-gel method,and then the active component V₂O₅ was supported by impregnation method.The experimental results show that S and N co-doping can effectively improve the denitrification performance.Through characterization analysis,it was found that the doping can significantly increase the specific surface area of the catalyst and make the pore size more refined;the surface of the catalyst is derivatized with more superoxide radicals and acidic sites;the surface acidity of the doped catalyst is enhanced by in-situ infrared analysis.In particular,the increase in Br?nsted acid sites is beneficial to increase SCR activity.Secondly,the TiO₂ carrier doped with rare earth metal Nd was prepared by sol-gel method.Then,the V₂O₅/TiO₂ catalyst doped with Nd element was prepared by impregnation with active component V₂O₅.The results show that the activity of VTiNd_1.0 catalyst is the best,especially the low temperature activity is obviously improved.XRD characterization results show that the characteristic peak intensity of anatase TiO₂ decreases and the crystallinity decreases with the increase of doping amount.The NH₃-TPD results show that the surface of Nd modified catalyst is more acidic and more acidic sites;H₂-TPR It was found that the reduction peak of VTiNd_1.0catalyst shifted to low temperature,indicating that the catalyst has better redox ability.At the same time,it was found that the concentration of adsorbed oxygen and V⁴⁺on the surface of Nd-doped catalyst was higher than that of undoped catalyst,active oxygen and more.The presence of a valence state is beneficial to improve the performance of the catalyst.In addition,the effects of different calcination temperatures on the denitrification performance of the catalyst were also investigated.It was found that the excessive temperature would lead to the formation of rutile phase TiO₂,while the temperature was too low,which would lead to incomplete calcination,and then the preparation conditions of the catalyst were optimized.The effect of reaction conditions on the denitration performance of the catalyst was also investigated.Among them,the sulfur and water resistance experiments show that S?N doping and Nd doping can effectively enhance the anti-poisoning ability of the catalyst.