Selective and regular localization of accessible Pt nanoparticles inside the walls of an ordered silica: Application as a highly active and well-defined heterogeneous catalyst for propene and styrene hydrogenation reactions

We describe here an original methodology related to the “build-the-bottle-around-the-ship” approach yielding a highly ordered silica matrix containing regularly distributed Pt nanoparticles (NPs) located inside the silica walls, Pt@{walls}SiO2. The starting colloidal solution of crystalline Pt nanoparticles was obtained from Pt(dba)2 (dba=dibenzylidene acetone) and 3-chloropropylsilane. The resulting nanoparticles (diameter: 2.0±0.4nm determined by HRTEM) resulted hydrophilic. The NPs present in the THF colloidal solution were incorporated inside the walls of a highly ordered 2D hexagonal mesoporous silica matrix via sol–gel process using a templating route with tetraethylorthosilicate, TEOS, as the silica source, and block copolymer (EthyleneOxide)20(PropyleneOxide)70(EthyleneOxide)20 (Pluronic P123) as the structure-directing agent. Low-temperature calcination of the crude material at 593K led to the final solid Pt@{walls}SiO2. Characterization by IR, HRTEM, BF-STEM and HAADF-STEM, SAXS, WAXS, XRD, XPS, H2 chemisorption, etc. of Pt@{walls}SiO2 confirmed the 2D hexagonal structuration and high mesoporosity (870m2/g) of the material as well as the presence of stable 2-nm-sized crystalline Pt(0) NPs embedded inside the walls of the silica matrix. The material displayed no tendency to NPs sintering or leaching (Pt loading 0.3wt.%) during its preparation.