Effect of Ce Ions Modification on NH3-SCR Reaction Performance of the Cu-SSZ-13 Catalyst
The Cu-SSZ-13 catalyst has been proved to be a high-efficiency NH3-SCR catalyst.However,it will still cause irreversible inactivation after severe hydrothermal aging(950 ℃).This paper reveals the relationship between the active sites and the catalytic activity of the Cu-SSZ-13 catalyst by investigating the effect of the concentration of the second metal ion(Ce)introduction on the properties of the active sites(copper sites,acid sites)and the catalytic activity.The results show that the Ce ion introduction in Cu-SSZ-13 does not become the active center of the NH3-SCR reaction,but only plays a role in regula-ting the position and quantity of Cu sites in the CHA cage and the amount of acid sites on the surface of the catalyst.Accord-ing to XPS,H2-TPR,NH3-TPD and activity analysis results,a small amount of Ce under low cerium loading(about 0.2％)can enter the ion exchange site,which is conducive to stabilizing the skeleton structure of SSZ-13 and inhibiting the formation of CuOx clusters(the degradation rate after aging at 950 ℃ is only 6％),it can also achieve high copper loading(3.01％Cu loading)and rich L acid and B acid sites,resulting in high NO conversion,wider reaction temperature window and excellent hydrothermal stability.Nevertheless,the introduction of excessive cerium ions has a negative effect on the catalytic activity and the hydrothermal stability of the Cu-SSZ-13 catalyst,leading to a decrease in SCR performance.
NETL
NSTL
万方数据
