Synthesis and Application of Nanowire Metal Catalysts in Hydrogenation Reaction

초록

The well organized mesoporous materials have extensive potential in the application over the last decade. Particularly nano-structured materials with a transition-metal oxide framework could be used as catalysts and electrode materials because of their unique properties. For selective applications, the potential would be maximized at a high crystalline state. These metals could be fabricated through the reverse replication method by controlling the concentration of introduced metal salts. The nano wire type metals obtained by replication method were employed as catalysts in the reduction of chiral butylronitrile and cyanobenzene to evaluate their catalytic activities in this work. The parent SBA-15 silica and its corresponding replica nano metals were characterized by X-ray powder diffraction, FE-TEM and FE-SEM. FE-SEM images revealed that as-synthesized nano metal and metal oxides consist of many rope-like wires with relatively uniform sized of ~2 μm, which are aggregated into wheat-like macrostructures. In this work, the nano wire metals were tested as a catalyst for the synthesis of (S)-3-pyrrolidinol-HCl salt from the optically active (S)-4-Chloro-3-hydroxybutyronitrile, and their activity was evaluated under the different reaction condition. The Ni-SBA-15 and Co-SBA-15 nano wires gave much superior activity to the bulk Co and Ni metal powders in the hydrogen reduction of cyano groups. It would be attributed to the well developed nano-sized crystalline structure of wire metals as shown in Fig.1(B). Those nano-wire metal catalysts could be recycled efficiently by magnet without filtration after use. Through many times repeated use, the catalysts retained the high activity without severe loss of activity.