【作者】 荆琪；

【导师】 吕秀阳；

【作者基本信息】 浙江大学 ， 化学工艺， 2007， 博士

【摘要】 随着不可再生资源的日益消耗，从可再生生物质资源尤其是木质纤维素类生物质出发制备新型平台化合物越来越引起关注。木质纤维素转化的途径之一是水解生成单糖(葡萄糖、木糖)，单糖再进一步分解生成化学品。其中单糖的生成和降解是影响整个反应过程选择性的关键步骤。木质纤维素水解一般采用液体酸作为催化剂，存在对设备腐蚀严重、污染环境等问题。围绕高温液态水中生物质资源绿色转化这一目标，本文开展了以下研究工作。利用搅拌高压反应釜研究了研究了压力10MPa，温度180℃至220℃范围内高温液态水中葡萄糖无催化分解反应动力学。实验结果表明：葡萄糖在实验范围内可完全分解，分解反应符合一级反应，分解反应活化能为118.85kJ／mol。反应主要产物为5—羟甲基糠醛、果糖、甲酸、乙酰丙酸和腐殖质。实验范围内5—羟甲基糠醛最大产率为32.0mol％，乙酰丙酸最大产率为2.0mol％。研究了压力10MPa、温度180℃至260℃范围内高温液态水中5—羟甲基糠醛无催化分解反应。实验结果表明，5—羟甲基糠醛在实验范围内可完全分解，分解反应符合一级反应，分解反应活化能为95.40kJ／mol。反应主要产物为甲酸、乙酰丙酸和腐殖质，同时还有两种未知产物需进一步定性。研究了压力10MPa、温度220℃至280℃和反应时间4h至32h范围内，高温液态水中乙酰丙酸稳定性。实验结果表明：高温液态水中乙酰丙酸很稳定，280℃、乙酰丙酸反应32小时，其转化率仅为7.0mol％。乙酰丙酸分解反应符合一级反应，分解反应活化能为31.29kJ／mol．在上述研究的基础上提出了10MPa，温度180℃至220℃范围内高温液态水中葡萄糖带有平行反应的一级连续降解动力学模型，从实验数据拟合得到了模型参数，模型计算值与实验数据符合良好，表明模型能很好地描述葡萄糖降解过程。研究了压力10MPa下，温度180℃至220℃范围内高温液态水中木糖无催化分解反应动力学。实验结果表明，木糖在实验范围内可完全分解，反应产物为糠醛、甲酸和腐殖质，糠醛最大产率为50.6mol％。提出了由木糖降解生成糠醛的带有平行反应的一级连续降解动力学模型，从实验数据拟合得到了模型参数，模型计算值与实验数据符合良好，表明模型能很好地描述木糖降解过程，木糖分解反应活化能为123.27kJ／mol。为了提高高温液态水中乙酰丙酸产率，本文探索利用35w大孔磺酸树脂催化葡萄糖或果糖制备乙酰丙酸。同时也研究了35w大孔磺酸树脂催化木糖制备糠醛。利用微型水热合成釜研究了130℃至160℃范围内，不同催化剂量、不同温度对乙酰丙酸产率的影响。实验结果表明：实验范围内树脂催化葡萄糖、果糖生成乙酰丙酸的产率均高于无酸催化下产率；葡萄糖生成乙酰丙酸的最高产率为27.4mol％，果糖生成乙酰丙酸的最高产率为49.7mol％。同时研究了140℃至160℃范围内，不同催化剂量、不同温度对木糖制备糠醛产率的影响。木糖生成糠醛的最高产率为26.3mol％。更多还原

【Abstract】 With the rapid consumption of non-renewable resources, the renewable biomass resources, in particular lignocellulosics biomass, has received more attention in producing chemicals. Lignocellulose may be converted to bulk chemicals by a hydrolysis reaction. During hydrolysis, the lignocellulose is cleaved to give monosaccharide, which can be decomposed further into useful chemicals. Results of most research showed that the first step (lignocellulose →monosaccharide) was a crucial step and had substantial impact on the selectivity and yield of chemical product. The traditional hydrolysis of biomass used liquid acid as catalysts such as hydrochloric acid and sulfuric acid, but the liquid acid had a negative impact on the reactor and on the global environment. Foucsing on the conversion of bimass in high temperature liquid water (HTLW), following study was did in this paper.Decomposition kinetics of glucose in HTLW was studied in the temperature ranges from 180 to 220℃ and pressure of 10 MPa with a stirred autoclave. The result showed that the glucose could decompose completely at experimental conditions. According to first order reaction mechanism, activation energy of non-catalyzed decomposition of glucose was 118.85 kJ/mol. The decomposition products were 5-hydromethylfurfural (5-HMF), fructose, levulinic acid (LA) and humic substance. At experimental conditions, the maximum yield of 5-HMF was 32.0 mol% and the maximum yield of levulinic acid was 2.0 mol%.Decomposition kinetics of 5-HMF in HTLW was studied at temperature ranges from 180 to 260℃ and pressure of 10 MPa. The decomposition products were formic acid, LA, two unknown products and humic substance. According to first order reaction mechanism, activation energy of non-catalyzed decomposition of 5-HMF was 95.40 kJ/mol.The stability of levulinic acid in HTLW was studied in the temperature ranges from 220 to 280 ℃ and pressure of 10 MPa. The result showed that the conversion of LA was only 7.0 mol% after 32 hours of reaction at 280 ℃. According to first order reaction mechanism, activation energy of non-catalyzed decomposition of LAwas 31.29kJ/mol.A kinetic model according to above experiments was proposed, in which decomposition kinetics of glucose in HTLW in the temperature ranges from 180 to 220℃ was described by a series first-order reactions with parallel by-reaction. The model parameters were correlated from the experimental data and the results calculated by the model were in well accordings with the experimental data.Decomposition kinetics of xylose in HTLW was studied at temperature ranges from 180 to 220℃ and pressure of 10 MPa. The decomposition products were furfural, formic acid and humic substance. The maximum yield of furfural was 50.6 mol%. A kinetic model was proposed, in which the process was described by a series first-order reactions with parallel by-reaction. The model parameters were correlated from the experimental data and the results calculated by the model were in well accordings with the experimental data. Activation energy of non-catalyzed decomposition of xylose was 123.27 kJ/mol.In order to improve the yields of levulinic acid in HTLW, 35w strong acid resin was used as an acid catalyst to prepare levulinic acid from glucose or fructose in this paper. Moreever 35w strong acid resin was also used to catalyze xylose to prepare furfural.The influence of temperature and catalyst loading on the levulinic acid yields in temperature ranges from 130 to 160℃ was studied using a small hydrothermal reactor. The result showed that by adding the resin, monosaccharide conversion was enhanced and levulinic acid formation was promoted. The maximum yield of levulinic acid formed from glucose was 27.4 mol%, and the maximum yield of levulinic acid formed from fructose was 49.7 mol %.The influence of temperature and catalyst loading on the furfural yields at temperature ranges from 130 to 160℃ was also studied. The maximum yield of furfural formed from xylose was 26.3 mol %.更多还原