Abstract
Development of hydrothermally stable,low-temperature catalysts for controlling nitrogen oxides emis-sions from mobile sources remains an urgent challenge.We have prepared a metal oxide-zeolite compos-ite catalyst by depositing Mn active species on a mixture support of CeO2/Al2O3 and ZSM-5.This compos-ite catalyst is hydrothermally stable and shows improved low-temperature SCR activity and significantly reduced N2O formation than the corresponding metal oxide catalyst.Comparing with a Cu-CHA catalyst,the composite catalyst has a faster response to NH3 injection and less NH3 slip.Our characterization re-sults reveal that such an oxide-zeolite composite catalyst contains more acidic sites and Mn3+species as a result of oxide-zeolite interaction,and this interaction leads to the generation of more NH4+species bound to the Brønsted acid sites and more reactive NOx species absorbed on the Mn sites.Herein,we report our mechanistic understanding of the oxide-zeolite composite catalyst and its molecular pathway for improving the low-temperature activity and N2 selectivity for NH3-SCR reaction.Practically,this work may provide an alternative methodology for low-temperature NOx control from diesel vehicles.
基金项目
National Natural Science Foundation of China(21976117)
National Natural Science Foundation of China(22125604)
National Natural Science Foundation of China(22276119)
Chenguang Program Shanghai Education Development Foundation and Shanghai Municipal Education Commission(21CGA48)
NETL
NSTL
万方数据