Study on the Denitrification Reaction Pathway of CeWTiOx Catalyst
CeWTiOx catalyst is recognized as one of the most promising catalysts for flue gas denitrification.To further clarify the reaction mechanism over it,the NH3-SCR(selective catalytic reduction)reaction process is studied.At the macroscale,the surface adsorption properties and reaction process of the CeWTiOx catalyst are investigated through transient and steady-state kinetic experiments,and the reaction activation energy is obtained.At the microscale,density functional theory calculations are employed to further investigate the reaction pathways of NH3 on the CeWTiOx catalyst surface.The results demonstrate that NH3 could be initially adsorbed on the CeWTiOx surface to form NH3 species and react with gaseous NO.The presence of gaseous oxygen could significantly promote the SCR reaction.Its reaction rate is nearly 1,0,and 0.25 order with respect to NO,NH3,and O2,respectively.DFT(density functional theory)calculations find that NH3 has a high adsorption energy on the W-Ce/TiO2(001)surface.It could be activated by dehydrogenation reaction to generate NH2* species.The adsorbed NH2* could can initially react with gas-phase NO to form the intermediate NH2NO,subsequently decomposing into N2 and H2O.In addition,NO could directly react with surface O to form NO2,which has a positive effect on the fast SCR reaction at low temperatures.In summary,the NO conversion reaction on CeWTiOx catalyst follows the Eley-Rideal mechanism.The modification of W further improves the performance of the catalyst.Therefore,the CeWTiOx catalyst is a promising material for efficient denitrification.
selective catalytic reduction(SCR)flue gas denitrificationCeWTiOxreaction kineticsdensity functional theory
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