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Silver Nanoparticles for Olefin Production: New Insights into the Mechanistic Description of Propyne Hydrogenation

Authors

  • Gianvito Vilé,

    1. Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)
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  • Dr. David Baudouin,

    1. Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)
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  • Prof. Ioannis N. Remediakis,

    1. Department of Materials Science and Technology, University of Crete, GR-71003 Heraklion (Greece)
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  • Prof. Christophe Copéret,

    Corresponding author
    1. Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)
    • Christophe Copéret, Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)

      Núria López, Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, E-43007 Tarragona (Spain)

      Javier Pérez-Ramírez, Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)

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  • Prof. Núria López,

    Corresponding author
    1. Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, E-43007 Tarragona (Spain)
    • Christophe Copéret, Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)

      Núria López, Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, E-43007 Tarragona (Spain)

      Javier Pérez-Ramírez, Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)

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  • Prof. Javier Pérez-Ramírez

    Corresponding author
    1. Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)
    • Christophe Copéret, Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)

      Núria López, Institute of Chemical Research of Catalonia, ICIQ, Av. Països Catalans 16, E-43007 Tarragona (Spain)

      Javier Pérez-Ramírez, Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich (Switzerland)

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Abstract

The gas-phase partial hydrogenation of propyne was investigated over supported Ag nanoparticles (2–20 nm in diameter) prepared by using different deposition methods, activation conditions, loadings, and carriers. The excellent selectivities to propene attained over the catalysts, exceeding 90 %, are independent of the particle size but the activity is maximal over approximately 4.5 nm Ag particles. Certain kinetic fingerprints of Ag, such as the positive dependence on the alkyne pressure, the relatively low reaction order in H2, and the low apparent activation energy, deviate from those of conventional hydrogenation metals such as Pd and Ni, questioning the applicability of the classical Horiuti–Polanyi scheme. Periodic dispersion-corrected density functional theory (DFT-D) calculations and microkinetic analysis demonstrate the occurrence of an associative mechanism, which features the activation of H2 on the adsorbed propyne at structural step sites. By using the atomistic Wulff model, the number of B5 sites available on the Ag nanoparticles was estimated to be maximal in the size range of 3.5–4.7 nm. The rate of propene production correlates with the density of B5 sites, which suggests that the latter are potential active centers for the reaction. This alternative pathway broadens the mechanistic diversity of hydrogenation reactions over metal surfaces and opens new directions for understanding metals that do not readily activate H2.

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