Browsing by Author "Kemball, Charles"

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    Interactions of Dienes and Alkynes with Rutile (Titanium Dioxide)
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (09), 1974) Halliday, Marlene M.; Kemball, Charles; Leach, H. Frank
    The catalytic properties of titanium dioxide (rutile) have been examined for a number of reactions involving dienes (propadiene and buta-1,3-diene) or alkynes (ethyne, propyne and but-2-yne) with hydrogen, deuterium or deuterium oxide. The isomerization of propadiene to propyne and the exchange of the methine hydrogen atom of the latter with deuterium oxide occur below 370 K. The main reaction with all the compounds, but particularly the alkynes, was a loss of hydrocarbon to the surface at 470 K or above to form a residue which was probably oligomeric. This process was accompanied by some formation of alkenes from buta-1,3-diene and to a much smaller extent from the alkynes; the reaction was not affected by the presence of gas phase hydrogen or deuterium and was essentially a self-hydrogenation of the unsaturated compounds. Water inhibited the formation of residue and the self-hydrogenation of buta-1,3-diene, and an exchange reaction occurred if deuterium oxide was used. The influence of various pretreatments on the catalytic properties of titanium oxide were examined and possible intermediates for some of the reactions are proposed.
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    Poisoning of a Supported Molybdenum Olefin Disproportionation Catalyst
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (07), 1974) Howe, Russell F.; Kemball, Charles
    Nitric oxide and carbon monoxide have been used to poison a propene disproportionation catalyst prepared from molybdenum hexacarbonyl on silica. Nitric oxide is strongly adsorbed, and an effective poison, but infra-red spectra indicate that adsorption occurs on more than one type of site, so that estimates of the active sites obtained are upper limits only. The nitric oxide poisoning experiments have shown that molybdenum is well dispersed on the silica support. Carbon monoxide is not strongly adsorbed; the slight poisoning effect observed can be accounted for in terms of competition between gas phase carbon monoxide and propene for the active sites.