Hydrothermal stability of different zeolites in supercritical water: Implication for synthesis of supported catalysts by supercritical water impregnation

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Date: Sept. 2018
From: Korean Journal of Chemical Engineering(Vol. 35, Issue 9)
Publisher: Springer
Document Type: Report
Length: 290 words

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Abstract :

To access, purchase, authenticate, or subscribe to the full-text of this article, please visit this link: http://dx.doi.org/10.1007/s11814-018-0084-y Byline: Yuechao Zhang (1), Yingjie Li (1), Junjie Gu (1), Senlin Tian (1), Ping Ning (1) Keywords: Supercritical Water Impregnation; Supported Catalysts; Hydrothermal Stability; Zeolite Supports Abstract: Supercritical water (SCW) impregnation is an efficient and feasible method that has been used to prepare highly dispersed supported catalysts, but few studies have investigated the stability of support materials in supercritical water. Thus, our aim was to investigate the hydrothermal stability of zeolite supports (ZSM-5, TS-1, ZSM-35, HY, 13X, Beta, SAPO-11 and SAPO-34) as model compounds in supercritical water. Results showed that almost all of zeolites suffered from crystallinity change, structural properties degradation, obvious desilication and dealumination. The decrease of surface areas and the collapse of crystalline structures in HY, 13X, Beta, SAPO-11 and SAPO-34 were more serious compared to ZSM-5, ZSM-35 and TS-1. The micropore areas and acidity of all SCW-treated zeolites were reduced. 13X with lower Si/Al ratio had higher hydrothermal stability than HY due to the formation of extra-framework Al (EFAL). EFAl also generated strong Lewis acid sites determined by ammonia temperature-programmed desorption and 27.sup.Al magic angle spinning nuclear magnetic resonance. Desilication and dealumination were simultaneous, and led to the increase of framework Si/Al ratio. ZSM zeolites (ZSM-5, ZSM-35 and TS-1) had higher hydrothermal stability than HY, 13X, Beta, SAPO-11 and SAPO-34 in SCW. Author Affiliation: (1) 0000 0000 8571 108X, grid.218292.2, Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China Article History: Registration Date: 15/06/2018 Received Date: 05/03/2018 Accepted Date: 11/05/2018 Online Date: 20/06/2018 Article note: Electronic Supplementary Material Supplementary material is available for this article at https://doi.org/10.1007/s11814-018-0084-y and is accessible for authorized users.

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Gale Document Number: GALE|A552980270