高温液态水预处理木质纤维素类生物质的实验研究

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	高温液态水预处理木质纤维素类生物质的实验研究
其他题名	The Study on Hot Liquid Hydrolysis of lignocellulosic biomass
	徐明忠
导师	袁振宏
	2008-06-03
学位授予单位	中国科学院广州能源研究所
学位授予地点	广州能源研究所
学位名称	硕士
关键词	高温液态水水解木质纤维素类生物质水解动力学水解反应器
摘要	木质纤维素类生物质制取燃料乙醇已经成为全世界的研究热点，酶水解是最高效的处理纤维素的方法。然而酶水解受到木质纤维素稳定结构的影响，需要对原料进行预处理。高温液态水预处理利用高温液态水的酸碱自催化功能，能够高效地溶解半纤维素，保留纤维素，实现预处理。为更好地研究在高温液态水在预处理中的水解机理，并为连续式水解反应装置的设计提供必要数据，本文在总结国内外燃料乙醇现状和木质纤维素预处理燃料乙醇技术现状的基础上，首先在间歇和渗滤条件下以广州本地的稻杆为原料，研究了高温液态水水解的最佳工况，并对产物进行了分析；之后选取木聚糖作为半纤维素模化物，稻杆和棕榈壳作为草本与木本生物质的代表进行了关于水解动力学数学模型的研究，经过计算拟合得到了相关动力学参数；最后以前面的数据为基础设计计算了两段式连续水解反应器。实验表明，间歇条件下较优工况是：稻杆在温度为200℃，压力4.0MPa，液固比为20:1，搅拌转速为500 r/min的条件下经过预热60min达到反应条件后保持10min，产物还原糖浓度达到8.9g/L，还原糖转化率达到51.85%，原料转化率达48.18%。渗滤条件下较优工况是：稻杆在160℃，液固比为20:1的条件下，经过水解42min达到最大糖浓度6.23g/L，还原糖转化率为41.53%。通过对间歇最佳工况条件下的固体残渣进行范式分析、电镜扫描以及工业分析和元素分析发现，半纤维素转化率达88.90%，纤维素只损失了5.72%，同时溶解了20.18%的木质素和33.05%的灰分。电镜扫描下残渣的孔隙率要大于原料，松散度也增加。工业分析与元素分析显示残渣的热值提高了221.2kJ/kg，挥发份和灰分都有所降低。在总结了国内外半纤维素水解模型的基础上，采用假一级均相反应模型，对木聚糖（半纤维素模化物）、稻杆、棕榈壳的试验数据进行模拟，计算得到了动力学参数。其中木聚糖降解的活化能为65.58kJ/mol，其单糖降解活化能为147.21kJ/mol；相对应地稻杆和棕榈壳的参数分别为68.76kJ/mol和47.08kJ/mol、95.19kJ/mol和79.74kJ/mol。计算得到的数学模型与实验数据基本吻合。最后，在间歇实验的基础上，结合国内外水解反应器的研究，设计计算了两段式连续超低酸水解装置，第一段为水平推流式，第二段为垂直逆流式，设计处理量为20kg/h。为后续该技术的工业化应用打下基础。
其他摘要	Lignocellulosic biomass has been widely applied to produce ethanol. Enzymatic hydrolysis has been proved to be the best way to hydrolysis cellulose. However, due to the stability of lignocellulosic biomass’s structure, the raw materials should be pretreated. Hot liquid water can efficiently hydrolyze hemicellulose and reserve cellulose, considerd to be a competitive pretreatment process. In order to study the hydrolysis merchanism and providing datas for the continuous hydrolysis reactor desgin, a review of world ethanol was promoted. Then local rice straw was investigated on the best condition by liquid water batch hydrolysis and the products were analyzed. Furthermore, xylan, rice straw and palm shell were hydrolyzed under the best condition to meet the math model, and the kinetic parameters were canculated. Finally a continuous reactor for biomass hydrolysis was designed based on the above datas. The effect of reaction temperature and time, the mass ratio of liquid to solid ratio(L/S), rotating speed and preheating time on the suagr yield, concentration and raw material conversion ration had been investigated by hot liquid water batch hydrolysis of rice straw.The optimum hydrolysis conditions from a comprehensive consideration haver be determine as follows. The temperature was 200℃, and the presssure was 4.0MPa.The ratio of liquid to solid ratio was 20 and the reaction time was 10 minutes.Furthermore, the rotating speed was 500r/min and preheating time was 60 minutes.The liquid product had a sugar concentration of 8.9g/l and a sugar yield up to 51.85%, as well as a mass conversion ratio of 48.18%. The bed-shrinking percolation experiments indicated that under the condition of temperature at 160℃, L/S at 20:1 and time at 42 minutes, the maximal sugar concentration was obtained at 6.23g/l and the sugar yield was 41.53%. The residue was test by Van Soest methods that the conversion ratio of hemicellulose, cellulose, lignin and ash were 88.90%, 5.72%, 20.18% and 33.05 % respectively. A SEM test and industrial and element analysi were carried out on the residue under optimal condition to identify the hydrolysis result. The results showed that the pretreatment was efficient. A first-oder squential kinetic modeling of hot liquid water hydrolysis of xylan, rice straw and palm shell were employed on the basis of kenetic experiment data and summarization of all models on hemicellulose hydrolysis.The kinetics were caculated as following: The active energy of hemicellulose degradation were 65.58kJ/mol for xylan, 68.76kJ/mol for rice straw and 95.19kJ/mol for palm shell; The active energy of sugar degradation were 147.2kJ/mol, 47.08kJ/mol for rice straw and 79.74 for palm shell. The caculated results meet approximately with the experiment data. Based on the data of batch experiments, with combination of summarization on the hydrolysis reactor styles, a two-stage continuous reactor of a capacity of 20kg/h were scheme out.The first stage was a horizonal plug flow reactor which hydrolyzed hemicellulose with hot liquid water. The second stage used a vertical countercurrent bed to achieve high celluose conversion by extremely low acid hydrolysis.
页数	67
语种	中文
文献类型	学位论文
条目标识符	http://ir.giec.ac.cn/handle/344007/5812
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	徐明忠. 高温液态水预处理木质纤维素类生物质的实验研究[D]. 广州能源研究所. 中国科学院广州能源研究所,2008.

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