Water In Zeolites Research Articles

Quantitative microprobe analysis of hydrous minerals using OK? line. Estimation of water content in microarea

The electron microprobe analyses of muscovites and zeolites were carried out using OKα line in order to estimate the oxygen content attributed to water in zeolite or hydroxyl group in muscovite under electron bombardment area. Its content was determined by subtracting the oxygen content combined with metals stoichiometrically from the total content of it. The correction method used for the quantitative analyses here consisted of Duncumb-Reed atomic number correction, the new absorption correction proposed by the author and the Casting-Reed fluorescence correction. The number of OH in muscovite in the empirical formula obtained by this method was in good agreement with that of the ideal formula, and also in good agreement with the results given by the ignition loss. In the analyses of zeolites, their empirical formulas calculated from the results obtained by this method were found to be quite reliable, and the obtained water content agreed with the results of thermogravimetric analysis within 10% relative error.

A model of localized and nonlocalized adsorption for the system of water and methanol in a-type zeolite.

A model of localized and nonlocalized adsorption for the system of water and methanol in a-type zeolite.

Sorption of hydrocarbons and water in silanated and unsilanated partial H-forms of zeolite Y

A study has been made of sorption at 30°C of n-hexane, 2-methylpentane, 2,2-dimethylbutane, cyclohexane, benzene and water in zeolite Y with 0, 31, 54 and 73% of the Na replaced by H, both before and after silanating these sorbents to different extents. Hydrocarbons were sorbed at 63 ± 2 Torr and water at 10 Torr. The three unsilanated partially H-exchanged forms of Y, in formation from Na–Y, each lost nearly the same fraction of sorption capacity for hydrocarbons and water as compared with Na–Y. It is suggested that regions of impermeable amorphous material had formed in similar amounts in each partial H-form, nucleated and developed on or in a matrix of parent crystal, as a result of bond breaking and re-making with different partners, associated with proton migration. Compared with the corresponding unsilanated form the silanated 31 and 54% H-exchanged Y gave enhanced uptakes. This was attributed in part to increased sorption energy because of interaction of sorbate not only with lattice atoms but also with the extra atoms introduced by silanation and subsequent reactions. While the silanated 31 and 54% H-exchanged Y freely sorbed all the hydrocarbons and water the silanated 73% H-forms were heavily blocked. Possible causes of this strong difference were discussed.

Investigation of surface phenomena on solid catalysts by simultaneous TG and DTA

Simultaneous thermogravimetry and DTA were used to investigate the phenomena of adsorption, desorption and surface reactions of water vapour on NaX and NaYtype and NaX-exchanged zeolites, and silica and alumina gels treated with sodium hydroxide. On the basis of the quantitative results, it was possible to give an interpretation of the surface phenomena and to establish the existence of various active centres on the surface of the catalysts. Water in zeolites is probably bound by oxygen-alkali metal bonds.

The low apparent permittivity of adsorbed water in synthetic zeolites

The low apparent permittivity of adsorbed water in synthetic zeolites

Proton magnetic resonance line shapes of water and ammonium ions in type-Y zeolites

Proton magnetic resonance line shapes of water and ammonium ions in type-Y zeolites

The state of water in Y-type zeolites

By titration with Fischer's solution and thermodesorption the authors show that the firmly combined water conteat of Y-type zeolites depends on the nature of the ion-exchange cation and the heat-treatment conditions.

The mobility of water in zeolites—II: Self-diffusion of water in synthetic NaP zeolite

Self-diffusion parameters for water in synthetic NaP zeolite have been measured using a radiochemical technique. This has permitted detection of a marked increase in the rate as self-diffusion proceeds. The sudden change in rate can be attributed to a low-energy structural change occurring in the zeolite under the hydrothermal experimental conditions.

The mobility of water in zeolites—I: Self-diffusion of water in analcite

Self-diffusion parameters of water in the zeolite analcite (Na 2O, Al 2O 3, 4SiO 2, 2H 2O) have been measured by a radiochemical technique. The rate of self-diffusion was found to be slow and comparisons to water migration in other zeolites were made. The relevance of the results of previous studies of cation migration has been discussed.

Intracrystalline rearrangement of constitutive water in hydrogen zeolite Y

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntracrystalline rearrangement of constitutive water in hydrogen zeolite YGeorge T. KerrCite this: J. Phys. Chem. 1967, 71, 12, 4155–4156Publication Date (Print):November 1, 1967Publication History Published online1 May 2002Published inissue 1 November 1967https://doi.org/10.1021/j100871a079RIGHTS & PERMISSIONSArticle Views550Altmetric-Citations156LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (196 KB) Get e-Alerts

905. Water in hydrates. Part II. Light and heavy water and sulphur dioxide in synthetic zeolites

905. Water in hydrates. Part II. Light and heavy water and sulphur dioxide in synthetic zeolites

327. Diffusion and sorption of water in zeolites—I. Sorption: R. M. Barrer and B. E. F. Fender, J. Phys. Chem. Solids, 21 (1/2), Oct. 1961, 1

327. Diffusion and sorption of water in zeolites—I. Sorption: R. M. Barrer and B. E. F. Fender, J. Phys. Chem. Solids, 21 (1/2), Oct. 1961, 1

The diffusion and sorption of water in zeolites—I. Sorption

Equilibrium sorption measurements have been made for D 2O and H 2O in the crystalline zeolites chabazite, gmelinite and heulandite, at relative coverages greater than θ = 0.85. The water contents, the shape of the isotherms, the isosteric heats and the partial molar entropies are almost identical for H 2O in chabazite and gmelinite; in heulandite isotherms are more rectangular but isosteric heats and partial molar entropies do not differ greatly from those in the other zeolites. Differences in these properties as between sorbed D 2O and H 2O are small, but heats of sorption are slightly greater for D 2O and slightly larger molar amounts of D 2O are probably sorbed in the crystals at the same relative pressures and temperatures. The sorbed water has certain fluid-like characteristics as shown by the similarity of the thermal entropies of sorbed and liquid water and by the thermal expansivities of sorbed water in chabazite and gmelinite. In heulandite there is some evidence from the thermal expansion data that the aluminosilicate lattice is sensitive to small changes in water content.

The diffusion and sorption of water in zeolites—II. Intrinsic and self-diffusion

The solution of three-dimensional diffusion equations is discussed with respect to the applicability of a √ t relationship to describe diffusion. The kinetics of the rates of H 2O sorption and of D 2O-H 2O exchange have been followed in the zeolites chabazite, gmelinite and heulandite in the temperature range 30–80°C, and intrinsic diffusion coefficients and self-diffusion coefficients of water in the crystal evaluated from the respective sets of measurements. Self-diffusion coefficients in all three zeolites have values intermediate between the self-diffusion coefficients of liquid water, at the same temperature, and ice near its melting point. Small changes in total water content near saturation produce a slight decrease in the self-diffusion coefficients in chabazite and gmelinite and a more marked decrease in heulandite. Using equilibrium sorption data it is shown that the equation D = D∗ (dln a d lnc) is a reasonably satisfactory description of the relationship between the diffusion coefficients and this provides an indication that both intrinsic and self-diffusion processes involve molecules as diffusing units.