【作者】 曹云苹；

【导师】 张爱清；

【作者基本信息】 中南民族大学 ， 高分子化学与物理， 2011， 硕士

【摘要】 高分子负载催化剂,因其可以简化实验操作过程,有利于贵金属催化剂的回收和再生,环境污染小并且催化效率高,符合当今绿色化学的主题,因此被广泛用于固相有机合成中。本文制备了不同类型的交联型负载铂的高分子催化膜,并对其性能进行表征。将其应用于肉桂醛选择性加氢制备肉桂醇的反应中,以探讨不同交联度对催化反应的催化性能,及其与肉桂醇选择性的关系。具体包括以下几方面内容:1、以乙二醇为还原剂,聚甲基吡咯烷酮为稳定剂,用微波加热辐射法制备铂纳米簇,用TEM,XRD对其进行表征。结果表明微波辐射法制备的铂纳米簇稳定且分散均匀,粒径仅为3.7nm。另外,探讨了不同氢气压力下铂纳米簇对肉桂醛加氢反应的催化效果,用GC-MS对结果进行表征,证明当氢气压力为3MPa时,肉桂醛的转化率最高。2、用紫外光交联的方法制备不同交联度的SBS负载Pt的催化膜并探讨其对肉桂醛选择性加氢制备肉桂醇的催化效果。其中催化剂Pt纳米簇用微波法制备,膜载催化剂的负载量、光交联剂三羟甲基丙烷三丙烯酸酯(TMPTA)和光引发剂二苯甲酮(BP)的用量均为3%。用色谱-质谱联用,XRD,紫外分光光度计对膜载催化剂和反应产物进行了表征,结果表明,随着交联度的增加,肉桂醇的催化选择性先增后减,紫外光光照80s时,负载膜交联度23.63%,肉桂醛转化率为91.46,肉桂醇选择性80.98%。质谱分析表明交联度大于30%后,催化产物中开始有膜分解产生的小分子杂质出现,并随交联度的进一步增大而增多;显微镜检测同时说明此时膜结构发生变化,造成肉桂醇选择性的降低。3、运用简单的包裹制备不同交联度的负载铂的壳聚糖/戊二醛交联催化膜,并探讨其对肉桂醛选择性加氢制备肉桂醇的催化效果。其中Pt纳米簇用微波法制备,催化膜的交联度由戊二醛(GA)含量来控制。XPS显示Pt与CS膜之间存在配位作用。紫外光谱表明GA和CS产生了交联,并且交联度随着GA含量的增加而增加。用气相色谱-质谱联用对实验结果进行表征,结果表明,随着交联度的增加,肉桂醛的转化率和肉桂醇的选择性均先增后降,这是因为交联后期催化膜中开始有游离戊二醛的存在,这点由GC-MS检测证实。戊二醛与壳聚糖的含量比为1:1.0时,交联度为57.32%,此时肉桂醛转化率为70.13%,肉桂醇选择性为84.27%。更多还原

【Abstract】 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.更多还原