Supported Ionic Liquid Phase Containing Palladium Nanoparticles on Functionalized Multiwalled Carbon Nanotubes: Catalytic Materials for Sequential Heck Coupling/Hydrogenation Process

Well-dispersed palladium nanoparticles have been prepared in ionic liquids in the presence of 4-(3-phenylpropyl)pyridine under dihydrogen. These nanoparticles are immobilized onto multiwalled carbon nanotubes modified with imidazolium moieties (fCNTs). The resulting catalytic materials are tested in hydrogenation and Heck coupling reactions. Analogous Pd nanoparticles dispersed in ionic liquids have also been immobilized on silica for comparative purposes. fCNTs are found to be the best support for both hydrogenation and Heck coupling, being recycled up to four times without significant activity loss. Palladium nanoparticles supported on fCNTs are used as a single catalytic precursor for the C-C coupling/hydrogenation sequential process using [EMI][HP(O)(2)OMe] (EMI=1-ethyl-3-methyl imidazolium) ionic liquid phase without addition of supplementary base.