Investigation of Ce/BEA as a passive NO_(x)adsorber:2.Hydrothermal aging deactivation mechanism  

作　　者：Yiying Ding Minghui Yu Xiaojie Yu Meiqing Shen Jianqiang Wang Jun Wang Gurong Shen 

机构地区：[1]School of Chemical Engineering and Technology,Tianjin University,Tianjin,300350,China [2]School of Materials Science and Engineering,Tianjin University,Tianjin,300350,China [3]National Rare Earth Catalysis Research Institute,Dongying,257000,China

出　　处：《Journal of Rare Earths》2024年第8期1524-1530,I0004,共8页稀土学报（英文版）

基　　金：supported the National Key R&D Program of China(2021YFB3503200);the Innovative Research Groups of the National Natural Science Foundation of China(51921004);Young Elite Scientists Sponsorship Program by CAST(2021QNRC001);the Key R&D Project of Shandong Province(2021CXGC010703,2022CXGC020311)。

摘　　要：Ce/BEA has the potential to be applied as a novel passive NO_(x)absorber(PNA)in the after-treatment of vehicles due to its considerable NO_(x)storage capacity.However,as a vehicle exhaust after-treatment material,it must withstand the test of long-term hydrothermal aging.This work examined the deactivation mechanism of Ce/BEA during hydrothermal aging.3.0 wt%Ce/BEA was prepared using the ionexchange method,and then subjected to hydrothermal treatment at 650℃with 10%H_(2)O for 1-12 h to obtain samples with different aging extent.For comparison,the H-BEA support was aged under the same conditions.Brunauer-Emmett-Teller(BET)method,X-ray diffraction(XRD),NH_(3)temperature programmed reduction(NH_(3)-TPD),^(27)Al MAS nuclear magnetic resonance(^(27)Al MAS NMR),H_(2)temperature programmed reduction(H_(2)-TPR),and high resolution-transmission electron microscopy(HR-TEM)were performed to characterize the changes in PNA performance,structure,Ce species,and acidity.The HR-TEM and H_(2)-TPR results show that CeO_(x)particles appear after hydrothermal aging,which results from the detachment and aggregation of active Ce species.Based on the^(27)Al MAS NMR results,we conclude that BEA zeolite dealumination leads to the loss of acidic sites and the transformation of active Ce species on the acidic sites into the less active CeO_(x).This is the primary reason for the hydrothermal aging deactivation of Ce/BEA.

关 键 词：Passive NO_(x)adsorber Ce/BEA Hydrothermal aging CeO_(x) DEALUMINATION Rare earths 

分 类 号：X701[环境科学与工程—环境工程] TQ424[化学工程]