Effect of Dehydration on the Local Structure of Framework Silicon Atoms in Zeolites Y Investigated by Solid-State NMR Spectroscopy
IR@IIP: CSIR-Indian Institute of Petroleum, Dehradun
View Archive Info| Field | Value | |
| Creator |
Jiao,Jian
Ray,S.S Wang,W Weitkamp,J Hunger,Michael |
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| Date |
2009-06-23T06:52:45Z
2009-06-23T06:52:45Z 2009-06-23T06:52:45Z |
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| Identifier |
http://hdl.handle.net/123456789/248
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| Description |
Recently, high-field shifts of the Si(nAl) signals of 2 to
5 ppm occurring in the 29Si MAS NMR spectra of non-hydrated
zeolites Y were discussed to be caused by i) a variation of the local
structure of neighboring AlO4 tetrahedra or ii) the presence of
multivalent extra-framework cations. To clarify the reasons for
these resonance shifts, zeolites Y with different H- and Al-exchange
degrees were investigated by solid-state NMR spectroscopy. The
experimental results indicate that the primary reason for a highfield
shift of 29Si MAS NMR signals is the change of O-Al-O bond angles and Al-O bond lengths during the dehydration of AlO4
tetrahedra in the framework of zeolite Y. In contrast, the presence
of extra-framework aluminum cations leads only to a strong broadening
of the Si(nAl) signals, probably due to 29Si-27Al couplings,
and a weak high-field shift of not more than 1 ppm.
Keywords: Zeolites; NMR (29Si MAS) spectroscopy; Local structure;
Dehydration
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| Language |
en_US
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| Subject |
NMR
Zeolites Spectroscopy Dehydration |
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| Title |
Effect of Dehydration on the Local Structure of Framework Silicon Atoms in Zeolites Y Investigated by Solid-State NMR Spectroscopy
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| Type |
Article
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