首页|Investigation of Ce/BEA as a passive NOx adsorber:2.Hydrothermal aging deactivation mechanism

Investigation of Ce/BEA as a passive NOx adsorber:2.Hydrothermal aging deactivation mechanism

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Ce/BEA has the potential to be applied as a novel passive NOx absorber(PNA)in the after-treatment of vehicles due to its considerable NOx storage capacity.However,as a vehicle exhaust after-treatment material,it must withstand the test of long-term hydrothermal aging.This work examined the deacti-vation mechanism of Ce/BEA during hydrothermal aging.3.0 wt％Ce/BEA was prepared using the ion-exchange method,and then subjected to hydrothermal treatment at 650 ℃ with 10％H2O 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),NH3 temperature programmed reduction(NH3-TPD),27Al MAS nuclear magnetic resonance(27Al MAS NMR),H2 temper-ature programmed reduction(H2-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 H2-TPR results show that CeOx particles appear after hydrothermal aging,which results from the detachment and aggregation of active Ce species.Based on the 27Al 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 CeOx.This is the primary reason for the hydrothermal aging deactivation of Ce/BEA.

Passive NOx adsorberCe/BEAHydrothermal agingCeOxDealuminationRare earths

Yiying Ding、Minghui Yu、Xiaojie Yu、Meiqing Shen、Jianqiang Wang、Jun Wang、Gurong Shen

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School of Chemical Engineering and Technology,Tianjin University,Tianjin,300350,China

School of Materials Science and Engineering,Tianjin University,Tianjin,300350,China

National Rare Earth Catalysis Research Institute,Dongying,257000,China

Project supported the National Key R&D Program of ChinaInnovative Research Groups of the National Natural Science Foundation of ChinaYoung Elite Scientists Sponsorship Program by CASTKey R&D Project of Shandong ProvinceKey R&D Project of Shandong Province

2021YFB3503200519210042021QNRC0012021CXGC0107032022CXGC020311

2024

10.1016/j.jre.2023.05.009

稀土学报(英文版)
中国稀土学会

稀土学报(英文版)

CSTPCDEI
影响因子：1.3
ISSN：1002-0721
年,卷(期)：2024.42(8)
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