预处理对Ag/TS-1催化剂丙烯气相环氧化反应性能的影响
发表时间：2019-03-12
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- 论文类型：
- 期刊论文
- 第一作者：
- Li, Junjie
- 合写作者：
- Liu, Min,Guo, Xinwen,Xu, Shutao,Wei, Yingxu,Liu, Zhongmin,Song, Chunshan
- 发表时间：
- 2017-08-09
- 发表刊物：
- ACS APPLIED MATERIALS & INTERFACES
- 收录刊物：
- SCIE、EI、PubMed、Scopus
- 文献类型：
- J
- 卷号：
- 9
- 期号：
- 31
- 页面范围：
- 26096-26106
- ISSN号：
- 1944-8244
- 关键字：
- Al-zoned ZSM-5; enclosed hollow structure; distorted tetrahedral Al; dealumination-realumination process; reinserted Al; interconnected mesopore structure; MTP
- 摘要：
- ZSM-5 that uses TPAOH as a template has an Al-rich exterior and defective Si-rich interior; thus, a simple base leaching selectively removed the Si-rich interior while the Al-rich exterior was protected. This catalyst showed no change in stability comparing with parent ZSM-5 during the MTP reaction that was attributed to the enclosed hollow structure and richly acidic outer shell. A preliminary fluorination, however, both removed defective Si-sites and caused distortion in tetrahedral aluminum that made the outer shell susceptible to alkaline treatment. These distorted tetrahedral Al were mostly leached out by NaOH in 1 min. Furthermore, aluminum in the filtrate was slowly redeposited onto the zeolite, serving as external pore-directing agents to control silicon dissolution from the Si-rich interior. This dealumination-realumination alkaline treatment process led to a higher solid yield and a uniform opened-mesopore structure with mesopores around 13 nm in diameter. This material was characterized by SEM, TEM, N-2 adsorption, and mercury porosimetry.In addition, NH3-TPD, OH-IR, Al-27 MAS NMR, and H-1 MAS NMR results demonstrated that the reinserted Al were unlike the framework Al, contributing less to acidity. The dealumination-realumination process, therefore, was also capable of tuning the acidity of the mesoporous ZSM-5. This mesoporous catalyst exhibited a longer lifetime and a higher propylene selectivity than other catalysts with an enclosed mesopore structure.
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- 否
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