Efficient Synthesis of Monodisperse Metal (Rh, Ru, Pd) Nanoparticles Supported on Fibrous Nanosilica (KCC-1) for Catalysis

We report a simple and sustainable protocol for the synthesis of monodisperse rhodium (Rh), ruthenium (Ru), and palladium (Pd) metal nanoparticles supported on fibrous nanosilica (KCC-1). In this protocol, use of expensive dendrimers was replaced by inexpensive polyethylenimine (PEI) to produce highly monodispersed supported metal nanocatalysts. First, KCC-1 was covalently functionalized by PEI and then metal(II) salts were loaded on KCC-1-PEI material to have complexation of metal ions with amines of PEI. Reduction of metal(II) ions by NaBH4 yielded metal(0) nanoparticles supported on KCC-1. As-synthesized metal nanoparticles supported on PEI functionalized KCC-1, named KCC-1-PEI/Rh, KCC-1-PEI/Ru, and KCC-1-PEI/Pd, were characterized by transmission electron microscopy (TEM) for particle size and their distribution, N2 sorption studies for surface area, pore sizes and pore volume, thermogravimetric analysis for PEI loading, and solid state NMR for its covalent attachment. These nanocatalysts were then evaluated for the hydrogenation of phenylacetylene and styrene. They showed good catalytic activities under mild pressure, at room temperature and notably in a very short period of time. Catalysts were also recyclable several times with negligible loss of activity, indicating their good stability that is due to PEI functionalization as well as fibrous nature of KCC-1 support.