生物基多元醇高效氢解转化的Ru基催化体系构建及选择性调控研究

发布时间：2018-01-05 18:05

  本文关键词：生物基多元醇高效氢解转化的Ru基催化体系构建及选择性调控研究　出处：《上海应用技术大学》2016年硕士论文　论文类型：学位论文

  更多相关文章： 山梨醇 Ru基催化剂 氢解 碳纳米管 二元醇

【摘要】：二元醇是非常重要的聚酯类高分子单体,乙二醇、丙二醇等都可用于跟二酸反应,制得性能优良的聚酯材料,因而需求量与产量巨大。我国二元醇年需求量已超过700万吨,对外依存度高达86%,且其石油基生产路线难以持续。随着国家经济社会的发展,对二元醇的需求量日益增加,发展以生物质基糖醇等为原料的生物基二元醇生产新路线具有重要的现实意义。然而,在生物基碳水化合物的催化氢解反应过程中,高温和高氢压的强反应条件易导致目标产物选择性的下降。针对现行碳水化合物氢解制备二元醇过程中存在的反应温度高、产物选择性差等问题,本研究力图开发一种在温和条件下即有较高催化活性和选择性的碳水化合物选择氢解催化反应体系。据此,本文制备了不同载体负载的钌基催化剂,探索对该类催化剂活性中心和表面物化性质进行调变的方法,使得催化剂在保持对小分子裂解中间体较好加氢活性的同时,降低其对单糖分子的催化加氢活性,并研究碳水化合物在其表面的吸附与选择断键路径。取得的主要结果如下：(1)对于不同载体(分子筛、水滑石、类水滑石、碳纳米管)的催化剂,采用浸渍法制备的碳纳米管负载的Ru催化剂具有最高的加氢活性和最高的目标醇选择性。(2)对于以不同碳纳米管(氨基化、羧基化、羟基化、石墨化和原始)为载体的催化剂,官能化后更利于活性金属的负载。以山梨醇为底物,氢解反应活性顺序为Ru/ACNTs Ru/CNTs Ru/GCNTs Ru/CCNTs Ru/HCNTs.(3)以Ru/ACNTs为催化剂,添加不同碱助剂氢解山梨醇时,反应活性顺序为LiOH NaOH Ca(OH)2 CaO Mg(OH)2 Sr(OH)2 Ba(OH)2 KOH。综合考虑反应物转化率、收率和选择性,Ca(OH)2为最佳碱助剂。同时研究了碱助剂Ca(OH)2用量、催化剂用量、反应时间、反应温度、初始氢气压力等因素对山梨醇氢解反应的影响。在200℃、初始氢气压力5 MPa和反应时间2 h,碱助剂Ca(OH)2使用量0.5g,催化剂用量0.3 g时,山梨醇的转化率可达93.9%,甘油、1，，2-丙二醇和乙二醇的总收率达55.2%,总选择性达58.5%。
[Abstract]:Diol is a very important polyester macromolecule monomer, ethylene glycol, propylene glycol and so on can be used to react with diacid to produce polyester materials with good properties. The annual demand for diols in China has exceeded 7 million tons, the external dependence is as high as 86%, and its petroleum-based production route is not sustainable. With the development of national economy and society. The demand for diols is increasing day by day, so it is of great practical significance to develop a new route for the production of biological-based diols based on biomass based glycols. In the process of catalytic hydrogenation of biologically based carbohydrates. The high temperature and high hydrogen pressure could lead to the decrease of the selectivity of the target product. In view of the problems of high reaction temperature and poor product selectivity in the process of hydrogenolysis of carbohydrate to prepare diol. In this study, we tried to develop a carbohydrate selective hydrogenation catalytic system with high catalytic activity and selectivity under mild conditions. Based on this, ruthenium based catalysts supported on different supports were prepared. The method of modifying the active center and surface physicochemical properties of this kind of catalyst was explored, so that the catalyst could maintain better hydrogenation activity to small molecular pyrolysis intermediates and decrease its catalytic hydrogenation activity to monosaccharide molecules. The adsorption of carbohydrates on the surface and the selection of broken bond paths were studied. The main results are as follows: 1) Catalysts for different supports (molecular sieve, hydrotalcite, hydrotalcite, carbon nanotubes). The carbon nanotube supported Ru catalyst prepared by impregnation method has the highest hydrogenation activity and the highest target alcohol selectivity. 2) for different carbon nanotubes (amino, carboxylation, hydroxylation). The catalyst with graphitization and original) was more favorable to the loading of active metal after functionalization. Sorbitol was used as substrate. The order of hydrogenolysis activity is Ru/ACNTs Ru/CNTs Ru/GCNTs Ru/CCNTs Rur. HCNTs. 3) using Ru/ACNTs as catalyst. When different alkali additives were added in the hydrogenolysis of sorbitol. The order of reaction activity was LiOH NaOH Ca(OH)2 CaO Mg(OH)2 Sr(OH)2 Ba(OH)2 KOH.The conversion of reactants was taken into account. The yield and selectivity of CaOH _ (2) were used as the best base auxiliaries. The amount of Ca(OH)2, the amount of catalyst, the reaction time and the reaction temperature were also studied. The effect of initial hydrogen pressure on the hydrogenolysis of sorbitol was investigated. At 200 鈩

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