Catalytic Hydrogenation of CO2 to Formate Using Ruthenium Nanoparticles Immobilized on Supported Ionic Liquid Phases |
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Authors: | Savarithai Jenani Louis Anandaraj Liqun Kang Serena DeBeer Alexis Bordet Walter Leitner |
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Affiliation: | Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34–36, 45470 Mülheim an der Ruhr, Germany |
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Abstract: | Ruthenium nanoparticles (NPs) immobilized on imidazolium-based supported ionic liquid phases (Ru@SILP) act as effective heterogeneous catalysts for the hydrogenation of carbon dioxide (CO2) to formate in a mixture of water and triethylamine (NEt3). The structure of the imidazolium-based molecular modifiers is varied systematically regarding side chain functionality (neutral, basic, and acidic) and anion to assess the influence of the IL-type environment on the NPs synthesis and catalytic properties. The resulting Ru@SILP materials contain well-dispersed Ru NPs with diameters in the range 0.8–2.9 nm that are found 2 to 10 times more active for CO2 hydrogenation than a reference Ru@SiO2 catalyst under identical conditions. Introduction of sulfonic acid groups in the IL modifiers results in a greatly increased turnover number (TON) and turnover frequency (TOF) at reduced metal loadings. As a result, excellent productivity with TONs up to 16 100 at an initial TOF of 1430 h−1 can be achieved with the Ru@SILP(SO3H-OAc) catalyst. H/D exchange and other control experiments suggest an accelerated desorption of the formate species from the Ru NPs promoted by the presence of ammonium sulfonate species on Ru@SILP(SO3H-X) materials, resulting in enhanced catalyst activity and productivity. |
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Keywords: | CO2 hydrogenation formic acid/formate molecularly modified supports ruthenium nanoparticles supported ionic liquid phase (SILP)  |
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