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1H MAS studies of acid sites in ZSM-5 type zeolites

✍ Scribed by M. Hunger; D. Freude; H. Pfeifer

Publisher: Elsevier Science
Year: 1988
Tongue: English
Weight: 335 KB
Volume: 3
Category: Article
ISSN: 0920-5861
DOI: 10.1016/0920-5861(88)87035-4

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✦ Synopsis

Proton magic-angle-spinning nuclear magnetic resonance <lH MAS NMR) spectroscopy may yield quantitative information about Brbnsted acid sites, the extent of structural defects and non-framework species in the intra-zeolitic channels. We show that the extremely high concentration of silanol groups in TPA/ZSM-5 zeolites resonating+with a chemical shift of 1.4 -2.2 ppn should be assigned to a reaction of TPA ions with the framework during the synthesis and that the dealumination of the ZSM-5 framework leads to the appearance of non-framework AlOH species at 2.6 -3.6 ppn and strong Lewis centres. The latter give rise to a signal at 6.5 ppm observed in activated samples upon partial rehydration.

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