Browsing by Author "Jacobs, Peter A."

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    Surface Probing of Synthetic Faujasites by Adsorption of Carbon Dioxide: Part 1.—Infra-red Study of Carbon Dioxide Adsorbed on Na-Ca-Y and Na-Mg-Y Zeolites
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (6), 1973) Jacobs, Peter A.; Cauwelaert, Franz H. van; Vansant, Etienne F.; Uytterhoeven, Jan B.
    Infra-red spectroscopy of carbon dioxide adsorbed on Na-Ca(Mg)-Y faujasites is used to determine the distribution of Ca and Mg ions over the cation sites. Physisorption of CO2 provides a sensitive method for the detection of Ca2+ and Mg2+ in supercage positions. High temperature outgassing of the samples facilitates the migration of bivalent ions from positions in the supercage to the small cavities. Bivalent ions in the dehydrated Y samples are only present in the supercages when the degree of ion exchange is 46 to 48 % or higher. For high temperature chemisorption of CO2, the chemisorbed species are closely related to co-ordinated carbonate ions. The concentration of this species does not exceed 2 molecules per unit cell.
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    Thermal Stability of NH4-Chabazite
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (07), 1977) Beyer, Hermann K.; Jacobs, Peter A.; Uytterhoeven, Jan B.; Till, Ferenc
    The thermal stability of NH4-chabazite has been examined by i.r. spectroscopy and thermal analysis combined with mass spectrometry. Dehydration occurs in two and deammoniation in four steps. Disregarding a very small water loss during deammoniation, dehydroxylation is completely separable from deammoniation and occurs in two distinct steps. Two OH stretching bands at 3540 and 3630 cm–1 appear during deammoniation and could be related to distinct ammonium ions having bending vibrations at 1420 and 1460 cm–1 respectively. The hydroxyls showing a band at 3540 cm–1 are formed at lower temperatures and are less thermostable than other hydroxyls.