Journal Articles (before-1995)

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Subject: search.filters.subject.Infrared Spectra

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    Assignment of the Hydroxyl Bands in the Infrared Spectra of Zeolites X and Y: Part 2.—After Different Pretreatments
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (2), 1973) Jacobs, P. A.; Uytterhoeven, J. B.
    The i.r. absorption curve of “ deep bed ” calcined NH4Y zeolites could be broken down into the same components as HY zeolites. The frequency of the peaks was slightly changed, but their half band width remained constant. In a scries of treatments representing increasing hydrolysis non-acidic OH bands around 3680 and 3600 cm-1 increase in intensity, due to surface OH groups near Al defect locations. Polynuclear Al species bridging the cubo-octahcdra are suggested to be partly responsible for the increased thermal stability. The non-acidic OH bands in synthetic faujasites exchanged with polyvalent cations are explained on the same basis, since they behave in a similar way as the non-acidic bands on “ deep bed ” zeolites after different treatments.
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    Assignment of the Hydroxyl Bands in the Infrared Spectra of Zeolites X and Y: Part I.—Na—H Zeolites
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (2), 1973) Jacobs, P. A.; Uytteriioeven, J. B.
    The infrared spectra of zeolites X and Y were recorded in the hydroxyl stretching region under high resolution conditions. The samples varied in their Al and proton content. The spectra were broken down into six different components. The selection of this number of components was based on reproducible details appearing in the high resolution spectra. An assignment for the different components is proposed, which considers the four different types of oxygen ions as possible sites for proton location. The narrow band at 3650 enr1 is assigned to Ch—H hydroxyl groups, while the broad and asymmetric band at 3550 cm-1 contains components due to O2—H, O3—H and O4—H groups.
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    Infrared Spectra and Catalytic Activity of Supported Molybdenum Hexacarbonyl
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (12), 1972) Howe, R. F.; Davidson, D. E.; Whan, D. A.
    Infrared spectroscopy has been used to study the olefin disproportionation catalysts consisting of molybdenum hexacarbonyl supported on silica, alumina and magnesia. Activation of the catalysts is found to cause decomposition of the molybdenum hexacarbonyl. Decomposition occurs most readily on a silica support which is not able to stabilize intermediate sub-carbonyl species. The intermediate sub-carbonyl species observed on alumina and magnesia supports arc not active centres for olefin disproportionation ; the active species is formed by complete loss of all six carbonyl ligands. Indirect evidence suggests the active species is not molybdenum(O) but some higher oxidation state.