The state of water molecules in cubooctahedra of NaA, NaX and hydrosodalite

Oehme, Wolfgang; Michel, D.; Pfeifer, H.; Жданов, С. П.

doi:10.1016/0144-2449(84)90049-6

Cited by 13 publications

(7 citation statements)

References 13 publications

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“…45 The detailed analysis of the deuteron NMR spectra for water confined in the NaX and NaY zeolites, presented in this work, indicates that the presence of sodium cations in zeolite framework is particulary important for observed mobility of water molecules and stability of water clusters. Our results confirm some conclusions of Oehme et al 46 published a long time ago. Proton NMR spectra had been measured in hydrated zeolites in the range between 77 and 420 K. Careful analysis of the spectra and comparison with those obtained for hydrosodalites led to pointing out the stabilizing influence of sodium ions on the mobility of water molecules.…”

Section: ■ Concluding Remarkssupporting

confidence: 93%

Water Confinement in Faujasite Cages: A Deuteron NMR Investigation in a Wide Temperature Range. 1. Low Temperature Spectra

et al. 2014

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Deuteron NMR spectra were measured for D2O confined in NaX, NaY, and DY faujasites with various D2O loadings at temperatures ranging from T = 70 K to T = 200 K with the aim to study the molecular mobility of confined water as a function of Si/Al ratio and loading. The recorded spectra were fitted with linear combinations of representative spectral components. At low loading, with the number of water molecules per unit cell close to the abundance of sodium cations, a component related to π-jumps of water deuterons about the 2-fold symmetry axis dominated. For loadings at levels 3 times and 5 times higher than the initial loading level, Pake dublets due to rigid water deuterons dominated the recorded spectra. A set of the quadrupole coupling constant values of localized water deuterons was derived from the analysis of the Pake dublets. Their values were attributed to deuteron positions corresponding to the locations at oxygen atoms in the faujasite framework and locations within hydrogen-bonded water clusters inside faujasite cages. The contributions of the different spectral components were observed to change with increasing temperature according to the Arrhenius law with a characteristic dynamic crossover point at T = 165 K. Below T = 165 K a spectral component was observed whose contribution changed with temperature, yielding the activation energy of about 2 kJ/mol, characteristic for jumps between inversion-related water positions in clusters.

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Section: ■ Concluding Remarkssupporting

confidence: 93%

Water Confinement in Faujasite Cages: A Deuteron NMR Investigation in a Wide Temperature Range. 1. Low Temperature Spectra

et al. 2014

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“…However, the present observation that the four initially introduced molecules exclusively occupy the b-cages is at variance with literature reports. 14,15 According to these papers initially introduced water is also held in the supercages whereas on dehydration the final four molecules leaving the zeolite are found to come exclusively from the b-cages. Actually, in contrast to our experiments, the authors used deep-bed samples so that, probably, not sufficient time had elapsed to achieve thermodynamic equilibrium during adsorption.…”

Section: Distribution Of Water Between Beta-and Supercagesmentioning

confidence: 99%

“…1), about 240-260 water molecules have been reported to be accomodated at complete pore filling (300 K). 2,11 The results of several papers suggest that 32 of these molecules reside in the b-cages (4 H 2 O per cage), 2,[11][12][13][14][15][16] whereas all the others are in the supercages (26-28 H 2 O per cage) where the water is believed to form a liquid with dissolved cations.…”

Section: Introductionmentioning

confidence: 99%

A calorimetric and statistical mechanics study of water adsorption in zeolite NaY

Boddenberg

Rakhmatkariev

Wozniak

et al. 2002

Phys. Chem. Chem. Phys.

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“…The properties of water in zeolites have been examined in the past by XRD 9 or NMR. 10 These methods measure the average position of the molecule, and this may occasionally lead to inconclusive results. The answer to relatively simple questions, such as the number of water molecules and hydroxy units per cage, 11,12 is often ambiguous.…”

Section: Introductionmentioning

confidence: 99%

The Water Molecule in Na₆[AlSiO₄]₆ Sodalite

and

Metiu

2001

J. Phys. Chem. B

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The behavior of a water molecule in Na 6 [AlSiO 4 ] 6 sodalite has been investigated using density functional calculations. The lowest energy position of the molecule is near the plane of the 6-ring window which does not contain a Na ion. The molecule is oriented to form hydrogen bonds with two of the framework oxygens and to interact with a Na ion in a nearby window. In this configuration the energy is 0.58 eV below the energy of the isolated water molecule plus that of anhydrous sodalite. Several tests indicate that most of the binding energy is due to the interaction of the oxygen with the Na ion. An analysis of electronic density for the lowest energy position shows that, when the molecule is put in contact with sodalite, charge is transferred from the water molecule to the spaces between the hydrogen atoms and the framework oxygens and between the water molecule oxygen and the nearest Na framework ion. Other bonding sites are above the plane of a 6-ring window occupied by a Na ion and above a 4-ring window. † Part of the special issue "John T. Yates, Jr., Festschrift".

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The state of water molecules in cubooctahedra of NaA, NaX and hydrosodalite

Cited by 13 publications

References 13 publications

Water Confinement in Faujasite Cages: A Deuteron NMR Investigation in a Wide Temperature Range. 1. Low Temperature Spectra

Water Confinement in Faujasite Cages: A Deuteron NMR Investigation in a Wide Temperature Range. 1. Low Temperature Spectra

A calorimetric and statistical mechanics study of water adsorption in zeolite NaY

The Water Molecule in Na₆[AlSiO₄]₆ Sodalite

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The state of water molecules in cubooctahedra of NaA, NaX and hydrosodalite

Cited by 13 publications

References 13 publications

Water Confinement in Faujasite Cages: A Deuteron NMR Investigation in a Wide Temperature Range. 1. Low Temperature Spectra

Water Confinement in Faujasite Cages: A Deuteron NMR Investigation in a Wide Temperature Range. 1. Low Temperature Spectra

A calorimetric and statistical mechanics study of water adsorption in zeolite NaY

The Water Molecule in Na6[AlSiO4]6 Sodalite

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Product

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The Water Molecule in Na₆[AlSiO₄]₆ Sodalite