Monodisperse platinum nanoparticles of well-defined shape: synthesis, characterization, catalytic properties and future prospects

Monodisperse platinum nanoparticles with well-defined faceting have been synthesized by a modified polyol process with the addition of silver ions. Pt nanoparticles are encapsulated in mesoporous silica during in situ hydrothermal growth of the high surface area support. Removal of the surface regulating polymer, poly(vinylpyrrolidone), was achieved using thermal oxidationreduction treatments. Catalysts were active for ethylene hydrogenation after polymer removal. Rates for ethylene hydrogenation decreased in accordance with the amount of Ag retained in the Pt nanoparticles after purification. Ag is most likely present on the Pt particle surface as small clusters. Future prospects for these catalysts for use in low temperature selective hydrogenation reactions are discussed.