Embedding of Fine Particle Catalyst into Polymers and Its Catalytic Activity

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In current liquid-phase catalytic processe, fine particles of metals such as nickel or palladium are widely used as catalysts in suspended state. If these fine particle catalysts can be embedded into a polymer matrix without reducing their intrinsic activity, various benefits other than easy handling of catalyst will be acquired. For example, a new type of catalytic reaction system may be developed with utilizing the hydrophobic property of polymer.In this research, fine particle catalysts of Ru/carbon and Pd/carbon were embedded into silicone rrubbers and their catalytic activities were examined for the hydrogenations of acetone and unsaturated fatty acid. It was found that, though the reaction rates decreased by about an order of magnitude by embedding, the diffusion of reactants in silicone rubbers was very fast not to impede the reaction rate and that embedded catalysts catalyzed the reaction effectively with the effectiveness factor of catalyst being unity. The reduction in catalytic activity of embedded catalysts was presumed to result from the poisoning of the vapor generated on vulcanization and the filling of micropores of Ru/carbon catalyst with silicone rubber. On the other hand, the selectivity of the intermediate products of consecutive reaction was significantly decreased by embedding of catalyst into polymer, probably because of the cage effect by polymer molecules. These new findings will provide a new concept of the polymer-embedded fine particle catalyst.