Physicochemical and catalytic properties of Pt–poly(4-vinylpyridine) composites

Platinum was introduced to poly(4-vinylpyridine) (P4VP) using aqueous H2PtCl6 solution of pH 1.8. Several techniques (FTIR, Raman and X-ray photoelectron spectroscopy, extended X-ray absorption fine structure, X-ray diffraction, scanning electron microscopy) have been used to characterize the state of platinum species in Pt/P4VP composites. They showed incorporation of platinum mostly in the form of counterions, anionic complexes of Pt(IV) like [PtCl6]2− in which Cl− ligands predominated. Pyridinic-N of P4VP participates in the coordination of Pt(IV) species, however to definitively lower extent. Reduction of as-prepared Pt/P4VP composites by NaBH4 produces Pt-nanoparticles appearing in the form of irregularly shaped aggregates. Catalytic performance of reduced Pt/P4VP composites in the hydrogenation of unsaturated carbon–carbon bonds in alkene (2-butene-1,4-diol, B2-D) and alkyne (2-butyne-1,4-diol, B3-D) substrates is similar to that of commonly used inorganic oxide supported Pt-catalysts. However, in the presence of Pt/P4VP catalysts the formation of by-products via hydrogenolysis reaction is strongly suppressed owing to a lack of acidic properties of P4VP matrix.