DFT Study On CeSn DeNO_x Catalyst

The control of NOx has great significance to the improvement of atmosphere environment.As the most widely used and most effective method in NOx control,the key of Selective Catalyst Reduction of NOx by NH3(NH3-SCR)is the deNOx catalyst.The development of non-vanadium NH3-SCR catalysts with high efficiency has become a hot topic in air pollution control.At present,a large amount of metal oxide catalysts are used for NH3-SCR of NOx,and some of them showed high catalytic performances.However,the relationship between the structure and performance of new metal oxide catalysts remains unclear.The DFT calculations,which can be complemented by experiments,are useful method to reveal the relationship between the structure and activity as well as the reaction mechanism of NH3-SCR of NOx.Based on the obtained experimental results in our laboratory,the Ce-Sn composite oxide model catalyst was established.We studied the process of NH3 adsorption,the resistance against H2O and SO2 and the whole process of NH3-SCR reaction systematically by density functional theory calculations.In this study,theoretical calculations show that the dope of Sn atom on CeO2 promotes the adsorption behaviour of NH3 on CeO2 catalyst,which improves the NH3-SCR activity of the catalyst.In terms of water and sulfur resistance,CeSn catalysts has lower adsorption energy to H2O and SO2,compared to pure CeO2.Therefore,CeSn catalyst has high resistance against H2O and SO2,which is very important for the practical application.In the whole process of NH3-SCR reaction,we find that CeSn catalyst has relatively low activation energy,and the decomposition of NH2NO is the rate-determining step in the NH3-SCR process.The theoretical results obtained in this research are in good agreement with the obtained experimental results previously,and it shed light on the further modification of CeSn catalyst.