The Dynamic Structure of Gold Supported on Ceria in the Liquid Phase Hydrogenation of Nitrobenzene

Authors

  • Christiane Kartusch,

    1. Institute for Chemical and Bioengineering, ETH Zürich, Wolfgang-Pauli Strasse 10, 8093 Zürich (Switzerland), Fax: (+41) 44-633-12-52
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  • Martin Makosch,

    1. Institute for Chemical and Bioengineering, ETH Zürich, Wolfgang-Pauli Strasse 10, 8093 Zürich (Switzerland), Fax: (+41) 44-633-12-52
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  • Jacinto Sá,

    1. Institute for Chemical and Bioengineering, ETH Zürich, Wolfgang-Pauli Strasse 10, 8093 Zürich (Switzerland), Fax: (+41) 44-633-12-52
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  • Prof. Dr. Konrad Hungerbuehler,

    1. Institute for Chemical and Bioengineering, ETH Zürich, Wolfgang-Pauli Strasse 10, 8093 Zürich (Switzerland), Fax: (+41) 44-633-12-52
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  • Prof. Dr. Jeroen A. van Bokhoven

    Corresponding author
    1. Institute for Chemical and Bioengineering, ETH Zürich, Wolfgang-Pauli Strasse 10, 8093 Zürich (Switzerland), Fax: (+41) 44-633-12-52
    2. Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)
    • Institute for Chemical and Bioengineering, ETH Zürich, Wolfgang-Pauli Strasse 10, 8093 Zürich (Switzerland), Fax: (+41) 44-633-12-52

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Abstract

With regard to heterogeneous catalysis by gold and, in particular, hydrogenation reactions, there is no consensus on the oxidation state of the catalytically active species. By means of high-resolution X-ray absorption spectroscopy, we determined in situ the oxidation state of gold in the functioning catalyst Au/CeO2 in the slurry phase of the hydrogenation of nitrobenzene at high pressure. The conversion of nitrobenzene was monitored simultaneously by means of online attenuated total reflectance–Fourier transform infrared spectroscopy. We found that catalysts without measurable amounts of cationic gold were more active than catalysts with cationic gold. Any cationic gold that remained after pretreatment was reduced under reaction conditions, without any loss of activity. No evidence was found that the cationic gold contributed to the catalytic activity.

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