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Gold catalysed selective oxidation of alcohols in supercritical carbon dioxide

Kimmerle, Bertram ; Grunwaldt, Jan-Dierk ; Baiker, Alfons

In: Topics in Catalysis, 2007, vol. 44, no. 1-2, p. 285-292

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    Titre
    • Gold catalysed selective oxidation of alcohols in supercritical carbon dioxide
    Auteur
    • Kimmerle, Bertram. Department of Chemistry and Applied Biosciences, Institute of Chemical and Bioengineering, ETH Zurich, Hönggerberg, HCI, CH-8093, Zurich, Switzerland
    • Grunwaldt, Jan-Dierk. Department of Chemistry and Applied Biosciences, Institute of Chemical and Bioengineering, ETH Zurich, Hönggerberg, HCI, CH-8093, Zurich, Switzerland
    • Baiker, Alfons. Department of Chemistry and Applied Biosciences, Institute of Chemical and Bioengineering, ETH Zurich, Hönggerberg, HCI, CH-8093, Zurich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Topics in Catalysis, 2007, vol. 44, no. 1-2, p. 285-292. Kluwer Academic Publishers-Plenum Publishers
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:319915
    Summary
    The oxidation of benzyl alcohol to benzaldehyde over different supported gold catalysts in supercritical carbon dioxide has been investigated in a high-pressure batch reactor. Only molecular oxygen was used as oxidant and no base was needed. Different supports and preparation methods for the catalysts were tested and parameters like reaction temperature, pressure and molar ratios of the components were varied to study the catalytic behaviour. Gold colloids deposited on a titania support (1%Au/TiO2) yielded a conversion of 16.0% after 3h and a high selectivity to benzaldehyde of 99% under single-phase conditions. The reaction rate was significantly higher than in a corresponding "solvent-free” reaction without CO2. Even higher rates were found when a CO2-expanded phase was present. Monitoring of the oxidation in a high-pressure view cell via infrared transmission spectroscopy unravelled a slowdown of the reaction rate above 15% conversion. In addition, 1-octanol and geraniol were oxidised as well under similar conditions, yielding conversions of 4% and 10%, respectively, with selectivities towards octanal and geranial of 90% and 30%. Thus, the combined application of gold-based catalysts and supercritical CO2 offers an interesting alternative to the known methods of alcohol oxidation