【作者】 王杰；

【导师】 金放鸣；

【作者基本信息】 上海交通大学 ， 环境科学与工程， 2018， 博士

【摘要】 随着不可再生的化石能源的日益枯竭以及大量二氧化碳排放导致的温室效应的加剧,人们越来越多的开始关注和开发新的可再生的清洁能源。生物质是最重要的可再生资源,不仅能提供能源,而且能够提供碳、氢和氧等元素,通过催化转化可得到各种高附加值的化学品及燃料。因此生物质的转化利用具有重要的研究价值。本文选取自然界中最为丰富的生物质模型化合物碳水化合物及新一代生物质能源化合物微藻的模型化合物作为研究对象,探索高效催化转化其为高附加值化学品及燃料的方法。第二章主要研究了在水热条件下利用金属原位分解水产氢选择性还原葡萄糖制备高附加值多元醇（1,2-丙二醇,乙二醇和1,2-丁二醇）。通过对不同金属及催化剂的筛选,Zn和Pd/C表现出最好的催化效果:250 ^oC反应30 min,多元醇的总产量可达48%,其中1,2-丙二醇的选择性可达69.4%。通过对反应中间体的检测以及催化活性物质的研究,提出了可能的反应机理:葡萄糖首先异构化为果糖,然后果糖通过逆羟醛缩合断键后被还原为羟基丙酮,进而被还原为主产物1,2-丙二醇。Zn与水反应原位生成的ZnO与Pd/C有很强的协同催化作用,且ZnO在果糖的断键过程中起着关键作用。第三章研究了利用金属盐一步催化转化碳水化合物得到高附加值的乳酸烷基酯。通过对不同离子半径的金属盐进行筛选,发现Zn²⁺活性最高,以葡萄糖为原料乳酸乙酯和乳酸甲酯的最高产率分别为47.7%和50.8%,而以果糖和蔗糖为原料得到乳酸乙酯的最高产率分别为51.7%和47.5%。这是目前报道的从碳水化合物产乳酸乙酯的最高产率。根据对反应中间体及其与Zn²⁺离子的配合物红外图谱的检测,提出了相应的反应机理。金属盐催化剂对各个反应步骤的反应活化能计算结果表明,Zn²⁺在催化葡萄糖转化产乳酸乙酯的过程中反应活化能较低。虽然Zn²⁺在催化转化碳水化合物的过程中用量很少,但是考虑到Zn²⁺回收有一定的困难,且对环境有一定的危害风险,因此在第四章研究了负载型的路易斯酸催化剂催化转化葡萄糖产乳酸乙酯。通过对不同固体路易斯酸以及载体的筛选,发现ZnO/H-ZSM-5的催化效果最好,乳酸乙酯产率最高能达到40.5%,并且该催化剂制备和回收简单,在反应溶剂乙醇中稳定性好。通过BET和吡啶红外等研究发现催化剂载体及催化剂的路易斯酸性对催化效果具有决定性作用。而少量水的加入会显著提高乳酸乙酯的产率,但水的加入会导致ZnO的部分流失,这可能是导致催化剂回收再使用时催化效果降低的主要原因。第五章以生物质微藻模型化合物（高级脂肪酸）为原料研究了在非氢条件下通过脱羧来实现长链烷烃的制备,而所得的长链烷烃可广泛作为柴油的替代品。在水热条件下,不同载体及粒径的Ni基催化剂表现出了不同的脱羧活性。研究发现Ni基催化剂中Ni的粒径越小,长链烷烃的产率越高。当Ni/ZnO/AlO_n-500的Ni粒径达到6.5nm时,长链烷烃的最高产率为55%。催化剂的循环回收实验表明,二次回收的催化剂的脱羧产率会有降低。通过对催化剂的XRD图谱分析,发现脱羧反应完成之后催化剂中Ni的粒径会显著增大,这可能是催化剂循环使用后长链烷烃产率降低的主要原因。通过对反应产物分布的研究,提出了可能的反应机理。本研究利用廉价金属催化剂,实现了碳水化合物及微藻模型化合物到高附加值化学品/燃料的高效转化,避免了传统方法采用复杂催化剂、有毒试剂和高纯氢气等弊端。本文的研究为生物质的高效、经济和绿色利用提供了几种新方法。更多还原

【Abstract】 With the depletion of non-renewable fossil energy and excess emission of CO₂,which leading to the global warming,much attention was paid to the exploitation of renewable and clean energy.Biomass is the most important renewable energy.Not only energy,but also the elements of carbon,hydrogen and oxygen are provided,which could be catalytically transformed into high valuable chemicals and fuels.Thus,utilization of biomass is of essential research value.In this study,the model compounds of the most abundant biomass（carbohydrates）and new generation of biomass energy compounds（microalgae）were studied.And several novel methods of converting them to value-added chemicals/fuels were developped.Firstly,the reduction of glucose into high valuable polyols（1,2-propanediol,1,2-butanediol and glycol）with the in situ hydrogen from metal and water under hydrothermal condition was investigated.Among the different metals and catalysts,Zn and Pd/C gave the best yields of polyols（48%）and the selectivity of 1,2-propanediol（69.4%）after 30 min at 250^oC.Then,this study investigated the intermediates and the catalysts in the conversion of glucose to 1,2-propanediol.The possible mechanism was provided as following:glucose isomerized to fructose at first,and the cleavage of C-C bond through retro-aldol reaction and reduction leaded to acetol,which was reduced to1,2-propanediol at last.The in-situ formed ZnO worked as a synergistic catalyst with Pd/C and was the key catalyst in the cleavage of C-C in fructose.Secondly,we tried to convert carbohydrates into alkyl lactates in one pot with metal salts.After investigating different metal salts with various ionic radius,we found that Zn²⁺had the best catalytic effect.The best yields of ethyl lactate and methyl lactate from glucose are 47.7%and 50.8%,respectively.However,the yields of ethyl lactate from fructose and sucrose could reach 51.7%and 47.5%,separately,which were the best results from carbohydrates so far.Meanwhile,according to the intermediates and IR of the reactants with Zn²⁺,the possible mechanism was provided.At last,the activation energy of the conversion of glucose to 1,2-propanediol with different metal ions was investigated,the activation energy of the conversion of glucose to 1,2-propanediol with Zn²⁺could be obviously reduced.Although a small amount of Zn²⁺was added in the reaction,the recycle of Zn²⁺is not easy,which could lead to the environmental pollution.Thus,heterogeneous Lewis acid catalysts were developed to convert carbohydrates into ethyl lactate.After screening the solid Lewis acid and the supporters,ZnO/H-ZSM-5 gave the best yield of ethyl lactate,40.5%.Meanwhile,the preparation of ZnO/H-ZSM-5 are quite easy and ZnO/H-ZSM-5 was stable in ethanol with easy recycle.According to the BET and Pyridine-IR,the strong Lewis acidity and the supporter of ZnO were response to the high yield of ethyl lactate.A small amount of water added could improve the yield of ethyl lactate,while the leaching of ZnO was observed.And the leaching of ZnO might be the main reason for the decrease of yield of ethyl lactate with water in the recycling experiments.Thirdly,we tried to get long-chain alkanes,which were widly used as substitutes for diesel,by decarboxylation of microalgae model compounds（fatty acid）without hydrogen.A series of catalysts with Ni were prepared and tested under hydrothermal condition.The Ni catalyst with smaller particle size could give a better yield of long-chain alkane.Ni/ZnO/AlO_n-500 with 6.5 nm particle size of Ni gave the best result,55%yield of long-chain alkane.According to XRD,the particle size of Ni increased which might be response to the decrease of the yield of long-chain alkane with the recycled catalyst.And the possible mechanism of the reaction was provided according to the distribution of products.In conclusion,several biomass model compounds（carbohydrates and fatty acid）were successfully converted to value-added chemicals and fuels with simple metal catalyst.Complicated catalysts,toxic reagent and high purity hydrogen were avoided.This study provided several novel methods for the efficient,economical and green utilization of biomass.更多还原