Enhanced Low-Temperature Activity and Hydrothermal Stability of Ce-Mn Oxide-Modified Cu-SSZ-39 Catalysts for NH3-SCR of NOx
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Published:2023-12-21
Issue:1
Volume:14
Page:10
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ISSN:2073-4344
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Container-title:Catalysts
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language:en
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Short-container-title:Catalysts
Author:
Tang Ahui1, Yang Fuzhen1, Xin Ying1ORCID, Zhu Xiaoli1, Yu Long1, Liu Shuai1, Han Dongxu1, Jia Junxiu1, Lu Yaning1, Li Zhenguo2, Zhang Zhaoliang1ORCID
Affiliation:
1. School of Chemistry and Chemical Engineering, Shandong Provincial Key Laboratory of Fluorine Chemistry and Chemical Materials, University of Jinan, Jinan 250022, China 2. National Engineering Laboratory for Mobile Source Emission Control Technology, China Automotive Technology & Research Center Co., Ltd., Tianjin 300300, China
Abstract
Cu-SSZ-39 zeolite with an AEI structure exhibits excellent hydrothermal stability and can be a potential alternative to Cu-SSZ-13 zeolite SCR catalysts for NOx removal in diesel vehicles. However, the inferior low-temperature performance of Cu-SSZ-39 leads to substantial NOx emissions during the cold-start period, impeding its practical application. In this study, Ce-Mn oxide-modified Cu-SSZ-39 catalysts (CeMnOx/Cu-SSZ-39) and references (CeO2/Cu-SSZ-39 and MnOx/Cu-SSZ-39) were prepared by the ion-exchange of Cu ions followed by impregnation of the oxide precursors, with the aim of enhancing the NH3-SCR performance at low temperatures. The modified catalysts exhibited improved low-temperature activity and hydrothermal stability compared to the unmodified counterpart. In particular, CeMnOx/Cu-SSZ-39 showed the highest activity among the three catalysts and achieved NOx conversions above 90% within the temperature range of 180 °C to 600 °C, even after undergoing hydrothermal aging at 800 °C. Experimental results indicated that the synergistic effect between Ce and Mn in CeMnOx improves the redox properties and acidity of the catalyst due to the presence of Ce3+, Mn4+, and abundant adsorbed oxygen species, which facilitate low-temperature SCR reactions. Furthermore, the interaction of CeMnOx with Cu-SSZ-39 stabilizes the zeolite framework and hinders the agglomeration of Cu species during the hydrothermal aging process, contributing to its exceptional hydrothermal stability. The kinetics and NO oxidation experiments demonstrated that CeMnOx provides access to fast SCR reaction pathways by oxidizing NO to NO2, resulting in a significant increase in low-temperature activity. This study provides novel guidelines for the design and preparation of Cu-SSZ-39 zeolite with outstanding SCR performance over a wide temperature range.
Funder
National Natural Science Foundation of China China Postdoctoral Science Foundation Taishan Scholar Program of Shandong Shandong Provincial Natural Science Foundation National Engineering Laboratory for Mobile Source Emission Control Technology Project of Jinan Municipal Bureau of Science and Technology
Subject
Physical and Theoretical Chemistry,Catalysis,General Environmental Science
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