【作者】 阳光；

【导师】 周静红；

【作者基本信息】 华东理工大学 ， 化学工程， 2011， 硕士

【摘要】 作为地球上储存量最大的生物质能源及资源之一,糖类在自然界中的两种主要存在形式为纤维素和淀粉。通过均相或者非均相催化,以生物质来源的糖类为原料来制备化学品减轻对传统化石原料的依赖极具现实意义。然而使用贵金属为催化剂的氢解工艺投资成本大,限制了该工艺的应用和工业化。因此寻求一种热稳定性和催化活性优良的非贵金属催化剂对控制投资成本十分关键。研究发现过渡金属碳化物具有“类Pt”的性质,在催化加氢方面具有广阔的前景。在此基础之上,作者提出了过渡金属碳化物上葡萄糖催化氢解制备低碳二元醇的绿色工艺路线。本文首先建立了适合分析葡萄糖氢解产物的高效液相色谱方法。并通过碳热氢气还原合成了过渡金属碳化物催化剂,研究了双金属催化剂的催化活性。考察了碳化温度和载体对催化剂结构及其活性的影响,并对糖类的氢解机理进行了初步探索和讨论,主要的工作和结果如下：(1)选用Shodex公司的SC1211色谱柱建立了葡萄糖及其氢解产物的高效液相色谱分析方法,并对分析条件进行了优化。结果表明该方法在优化后的分析条件下,满足分离要求,经济简便,具有较高的准确度和精密度。(2)对葡萄糖氢解的操作条件进行优化,结果表明反应压力为10Mpa,反应温度为220℃反应半小时,葡萄糖转化率为48.5%,二醇收率为30.6%,目的产物选择性较高。(3)采用碳热氢气还原法分别制备了Ni、Co促进的碳化钨和碳化钼催化剂,发现碳化钨的反应活性要优于碳化钼,并且Ni促进的催化剂优于Co促进的催化剂。碳化温度为750℃时,活性相W2C基本完全形成,催化性能优于其他温度下制备的催化剂。以CNFs为载体的催化剂,活性相晶粒大,比表面积小,氢解反应活性反而比AC负载催化剂高。结果表明碳化钨催化剂的活性和选择性是随着晶粒增大比表面积减小而上升。(4)葡萄糖氢解产物溶液变色的原因是生成了少量的5-HMF,该物质在空气中氧化使溶液变成黄色。探讨了糖类氢解的逆向迈克尔反应机理和逆向羟醛缩合反应机理,从产物分布推出果糖是从分子中间断链得到两分子的三碳醇。而葡萄糖一部分首先转化为果糖发生氢解,得到1,2-丙二醇和甘油；另一部分在2、3碳原子和4、5碳原子之间直接断链从而得到两个碳原子的乙二醇。更多还原

【Abstract】 Carbohydrate, mainly existing in the form of cellulose and starch, is the largest biomass on the earth. Biomass-derived carbohydrates are employed as building blocks for the synthesis of fine chemicals via heterogeneous or homogenous catalytic processes. However, the cost of the process, using noble-metal as catalyst, limits the application and industrialization. In this way, it is worth exploring low-cost catalyst with good thermal stability and chemical performance for the possible control the investment of the process. Transition metal carbides have been identified as the potential catalysts to replace noble metal due to their behavior similar to the platinum catalyst for hydroprocessing.In this thesis, a reasonable analytical method was established for liquid products. Transition metal carbides for glucose hydrogenolysis were prepared by carbothermal hydrogen reduction (CHR). The hydrogenolysis mechanism and catalytic performance of different bi-metal carbides were studied. The influence of carburizing temperate and supports on the catalyst was investigated. The main work and results are as follows:(1) A high performance liquid chromatogram method was established to determine the concentration of products in glucose hydrogenolysis. The results shown that HPLC method, on condition of flow rate 0.5mL/min, temperate 50℃and solvent composite of CH3CN/H2O=4/6, fit the separation with high accuracy, precision and efficiency.(2) The operation conditions of hydrogenolysis were optimized. Under the conditions of pressure 10Mpa, temperate 220℃and residence time 30min, glucose conversion reached 48.5% with yield 30.6% of glycols.(3) Bi-metal carbides for glucose hydrogenolysis were prepared by carbothermal hydrogen reduction. Ni-W2C/CNFs was formed at 750℃showed better catalytic performance than Co promoted W2C or Mo2C, due to NiW alloy was synthetized during the carburizing process. It is proved that catalyst support on CNFs with larger crystal size and less surface area has higher selectivity than catalyst support on AC.(4) The formation of 5-HMF result in the yellow color of the products. The hydrogenolysis of fructose, compared with those of other carbohydrates, presented better selectivity to low carbon polyols with fewer by-products. The C-C cleavage happened in the middle of fructose while occurred between every second C of glucose.更多还原