Preparation, Characterization And Catalysis Of Polymer-protected Platinum Nano-clusters For Hydrogenation Of M-phenoxy Benzaldehyde

(1) Poly (N-vinyl-2-pyrrolidone) (PVP) protected nanoclusters of platinum were preparedby an ethanol reduction method and characterized through TEM, UV-VIS. It used as catalysts in the hydrogenation of m-phenoxy benzaldehyde (MPBD) to form high purity of m-phenoxy benzalcohol (MPBA) were studied. The results demonstrate that PVP-Pt displays high selectivity to MPBA.(2) Bimetallic nano-clusters were synthesized through the reduction of mixed salts bysodium borohydride. The addition of Co or Ru enhances the activity of the catalyst. The optimum catalysts can be achieved with a Pt/Co mole rate of 7:1 and Pt/Ru mole rate of 5:1. On the contrary, the addition of Cu, Au and Ni reduces the activity.(3) Polymer-protected platinum nano-clusters were modified by different metal ions. The activity hydrogenation of m-phenoxy benzaldehyde is promoted by the addition of Co2+, Fe2+, Ni2+. Under the optimum conditions, modified by Fe2+, its activity is one times higher than the platinum nano-clusters alone. Cu 2+ and Zn 2+ lead to lost the activity almost completely. Meanwhile the activity is effected by the concentration of PVP and pH value. When the ratio of PVP and Pt is 40 and the pH value equals to 4.3, the highest activity is obtained(4) The thermal decomposition behavior of PVP on platinum is studied, which is quite different from the pure PVP.TEM shows that nanoparticles by heating treatment is about 5nm. IR and element analysis reveal the residue of PVP also play stabilization action, but the structure of PVP has been changed.