Cation migration in zeolites: an in situ powder diffraction and MAS NMR study of the structure of zeolite Cs(Na)-Y during dehydration

Article Abstract:

A study examined cation migration and ordering in cesium-exchanged zeolite NaY. This research involved a joint Cs and Na MAS NMR spectroscopy and X-ray powder diffraction analysis of samples of cesium-exchanged zeolite NaY dehydrated at different temperatures under vacuum. The migration of cesium cations from the super to the sodalite cages was observed. Sodium was also seen to migrate from sodalite cages to the double six-rings and supercages. In addition, cation occupancies significantly varied within the cages at different temperatures in the dehydrated samples.

Cesium, Ions, Cations, Ion migration

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H MAS and 1H/27 Al TRAPDOR NMR studies of oxygen - zeolite interactions at low temperatures: probing Bronsted acid site accessibility

Article Abstract:

An extensive study using H MAS nuclear magnetic resonance spectroscopy was conducted to identify which Bronsted acid sites of zeolites are accessible to oxygen at low temperatures. Results show that large changes occur in the width of the spinning sideband envelopes of sites that are directly accessible to oxygen. It was also observed that these sideband envelopes carry information concerning the homonuclear and heteronuclear dipolar interactions.

Oxygen

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Determining the structure of trimethylphosphine bound to the Bronsted acid site in zeolite HY: double-resonance NMR and ab initio studies

Article Abstract:

Various experiments and calculations have been used to investigate the binding of trimethylphosphine to zeolite HY. Calculations showed that the neutral complex structure was more stable than the IP structure.

Usage, Magnetic resonance imaging, Acid-base chemistry

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