Fabrication And Characterization Of Pt Nano-cluster /Crosslinking Polymer Hybrid Membrane And Its Research For Selective Hydrogenation Of Cinnamaldehyde

Polymer-supported catalysts were used widely in recent years in organicsynthesis. This is because polymeric catalysts can make the reaction process simply, provide convenience of product purification, and provide for recovery and reuse of catalysts after reaction. They have low environmental hazards, recording the green chemistry now.In this work, we fabricated two kinds of Pt nano-cluster /crosslinking polymer catalysts (Pt/SBS, Pt/CS-GA) consisting of platinum group nano-clusters and crosslinking polymer (SBS, CS/GA) with the method of embedment. The structure and performance of hybrid membrane were characterized and analyzed. The catalytic membranes were used in the selective hydrogenation of cinnamaldehyde, finding the raletionship of crosslinking ratios and the selectivity for cinnamyl alcohol. The following three parts to be included in this paper:1. The stabile platinum nano-metal clusters were obtained with stabilizer Polyvinylpyrrolidone (PVP, K30) and reducing agent glycol by microwave irradiation (MW), which average diameter of particles was 3.7 nm. X-ray diffraction analysis showed the good crystalline form and stability of the platinum metal cluster. The characteristic of MW are short irradiation time and uniform heating. And MW can be applied to prepare a variety of nano-metal cluster.2. Photocrosslinked SBS membrane supported nano platinum catalysts were prepared and their catalytic activity on the selective hydrogenation of cinnamaldehyde was investigated. The platinum nanoclusters with an average diameter of c.a. 3.7 nm were obtained by reaction of H2PtCl6 with polyols, assisted by microwave irradiation (MW). The SBS membrane was loaded with 3.0 wt. % of Pt,BP, and TMPTA, respectively,and varing crosslinking ratios were achieved by adjusting the radiation time. The hydrogenation products were investigated by GC-MS and UV. As the crosslinking ratio increases, the selectivity for cinnamyl alcohol first increases, reaches 80.98% at a crosslinking ratio of 23.63%, and then decreases. Decomposition products of the SBS meambrane itself begin to appear as the radiaton time is over 30mins (corresponding to a crosslinking ratio of slghtly above 30%). The deterioration of the membrane structure is also evidenced by TEM measurement.3. The different crosslinking ratio glutaraldehyde/chitosan (GA/CS) membranes supported nano platinum catalysts were prepared and their catalytic activity on the selective hydrogenation of cinnamaldehyde was investigated. The stabile platinum metal clusters were obtained by microwave irradiation (MW). The CS membrane having different crosslink ratios were loaded with 6.0 wt. % Pt, and varing crosslinking ratios were achieved by adjusting the content of GA. There is reciprocity between Pt and GA/CS membrane by XPS measurement. As the crosslinking ratio increases, the selectivity for cinnamyl alcohol first increases, reaches 84.27% at a crosslinking ratio of 57.32%, and then decreases. This is because that the dissociative GA existed, same as the conversion of cinnamaldahyde.