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MAS-NMR spectroscopic study of water in zeolites

Authors
Journal
Journal of Molecular Catalysis
0304-5102
Publisher
Elsevier
Publication Date
Volume
27
Identifiers
DOI: 10.1016/0304-5102(84)85072-5
Disciplines
  • Chemistry

Abstract

Abstract Using the magic-angle spinning technique, ‘high-resolution’ proton NMR spectra of water in fully hydrated zeolites have been examined. The chemical shift of water was noted to vary in correlation with the Si/Al ratio. The variation is shown to reflect the composite effect of the disruption of hydrogen bonding between water molecules, and the interaction of water molecules with the lattice oxygen. The study also showed that the interparticle diffusion occurs at ambient temperature, while the intraparticle diffusion depends on the number and size of the cations. For highly siliceous zeolites (ZSM-5 and silicalite), it was shown that, while water molecules are located interstitially in ZSM-5, they are located on the extracrystalline surface of silicalite. The study has also demonstrated that water molecules in ZSM-5 zeolite are driven out of crystals by polar organic molecules, but not by non-polar organic molecules.

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