Browsing by Author "Christensen, Bjarne"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Carbonylation of Methanol and Ethanol on a Rhodium-Zeolite Catalyst
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (09-12), 1978) Christensen, Bjarne; Scurrell, Michael S.
    The carbonylation of methanol and ethanol on a rhodium-X zeolite has been studied. Particular emphasis has been placed on the effect of the concentration of the required alkyl iodide “promoter” on the selectivity of the reaction. A maximum in selectivity for carbonylation is observed for both alcohols as the alkyl iodide content of the reactant stream is increased. The side products are dimethyl ether and ethylene with methanol and ethanol respectively. Some comparative experiments with either rhodium-on-carbon or the unmodified NaX support show that at least for ethanol the zeolite support offers a sufficiently high activity to account for the rate of formation of side product under carbonylation conditions. For methanol carbonylation the necessity to employ near-stoichiometric quantities of methyl iodide and the effects which the absence of “promoter” has on catalyst behaviour are discussed. Comparison between the action of rhodium catalysts in homogeneous and heterogenised forms leads to the conclusion that close similarities in behaviour exist, probably due to the operation of a common mechanism.
  • No Thumbnail Available
    Item
    Selectivity of a Heterogeneous Rhodium Catalyst for the Carbonylation of Monohydric Alcohols
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (12), 1977) Christensen, Bjarne; Scurrell, Michael S
    The carbonylation activity of a heterogeneous rhodium-zeolite catalyst has been examined for the reactions of methanol, ethanol and propan-2-ol. A marked contrast in the behaviour of these three alcohols is seen. Selectivity for the carbonylation of methanol is high (>90 %) at all temperatures, whereas the sole reaction product with propan-2-ol is propene. Ethanol shows intermediate behaviour, exhibiting high selectivity (approaching 100%) for carbonylation at low temperatures, but very poor selectivity at higher temperatures. The results are consistent with the relative ease with which dehydration of the reactants occurs on polar catalysts.