Controlled synthesis of platinum loaded hierarchic silica spheres

Hierarchically structured macroscopic Pt-silica spheres were prepared in a one-step procedure using emulsion based sol-gel processing. The composition of the precursor solution was varied in order to study the influence of the Pt compound, the surfactant and the preparation method on the Pt particle size and concentration. Platinum was immobilized by coordination with an aminosilane and the nanoparticles were stabilized using different triblock copolymers. For removal of the surfactant, calcination as well as solvent extraction was used and the co-condensed samples were compared with silica spheres functionalized by ion-exchange. The activities of different catalysts were investigated in the methylcyclopentane ring opening reaction, which demonstrated a beneficial effect of the macroscopic shape and hierarchical structure of the support material. The simultaneous structural control over several scales of dimension from the macroscopic shape of the support to the nanometer size of the Pt nanoparticles allows the easy and highly reproducible synthesis of tailor-made catalysts.