论文总字数：17529字

摘 要

生物质具有可再生，低污染性，分布广泛资源丰富的特点，在资源日益匮乏的今天日益受到重视。而生物质中的纤维素是葡萄糖由糖苷键组成的长链分子，具有相当高的结晶度，这种稳固的结构使其很难水解，因此需要开发高效的水解手段。在此，本文对微晶纤维素在极性非质子溶剂丙酮-水体系中的降解规律开展研究，目的在于了解微晶纤维素在该体系中的降解规律和产物分布，进而通过条件优化，控制微晶纤维素的降解程度和产物分布。

本文的研究以均相反应器和聚四氟乙烯反应釜为主要设备。以极低浓度的硫酸作为水解催化剂，研究了微晶纤维素在不同反应时间，不同反应温度，不同酸浓度，不同丙酮浓度和不同液固比下的降解规律。经过数据整理和产物分析，结果表明：温度提高，有利于溶剂降解纤维素，整体呈现逐渐增大趋势，而葡萄糖的降解速率也随温度增长而逐渐提高，在温度高于180℃的条件下，葡萄糖得率反而降低；而随着时间延长，反应更加充分，纤维素降解率得以增加，有利于减少还原糖降解；H 浓度对改反应起到明显的催化作用，当H 浓度为0.01%时，生物质转化率有非常明显的提高，但是随着酸浓度提高，副产物的量不断增加；纤维素的降解速度随丙酮密度的增加而提高；丙酮浓度过高，水含量减少，会加剧还原糖的脱水反应，有利于还原糖降解生成糠醛类物质，副产物增加。丙酮浓度过低，会导致质子氢浓度增加，加剧水解副反应；液固比增大，纤维素降解率也随之增大，但相反葡萄糖得率迅速降低，不利于产物转化。最终优化出水解条件为：硫酸浓度为0.1%，丙酮浓度80%，液固比为10:1，反应温度180℃，保温反应时间60min。在此条件下微晶纤维素的降解率为61.15%.，其降解部分的总还原糖得率为88.78%，而纤维素降解的主要副产物为糠醛，乙酰丙酸，甲酸，乙酸，5-HMF。以上结果可为今后的深入研究提供参考和基本数据。

关键词：微晶纤维素 极性非质子溶剂 降解 丙酮

The degradation of cellulose in polar aprotic solvent system

ABSTRACT

Biomass is a renewable, low pollution, widely distributed resource, which has been paid more and more attention for resource deficiency. The biomass cellulose is composed of long chain molecules by glucose with glycosidic bonds and a high degree of crystallinity, the firm structure make it is difficult to be hydrolyzed. Therefore, it is necessary to develop efficient hydrolysis. In this paper, we studied the degradation process of microcrystalline cellulose in polar aprotic solvent system (acetone and water). The degradation products distribution of microcrystalline cellulose in the system were discussed, and the conditions were optimized, the microcrystalline cellulose degradation degree and product distribution were contolled.

The homogeneous reactor and PTFE reactor were used as the main equipment. The very low concentrations of sulfuric acid was used as hydrolysis catalyst, the effects of reaction time, reaction temperature, acid concentration, acetone concentration and ratio of liquid to solid on microcrystalline cellulose degradation were discussed. The results showed that the degradation of cellulose was increased with the temperature increasing, is conducive to solvent, showed gradually increasing trend, and the degradation rate of glucose also increased gradually with the temperature, when the temperature was higher than 180 ℃, the glucose yield was decreased. The reaction was more fully with the prolongation of time, cellulose degradation rate was increased and reduce reducing sugar degradation was also enhanced. The catalytic effect of concentration of H on the hydrolysis reaction was obviously. When the concentration of H was 0.01%, the biomass conversion rate was improved, however, the amount of byproducts were also increased. The degradation rate of cellulose increased with acetone content, when acetone content was increased too high, water content decreased, so by-product such as furfural and HMF increased. But when content of acetone was too low, amount of H increased, side reactions were enhanced. When liquid-solid ratio was increased, the rate of cellulose degradation also increased, but the glucose yield decreased rapidly, which was not conducive to conversion. The final optimized hydrolysis conditions as follows: sulfuric acid 0.1%, acetone content of 80%, liquid-solid ratio 10:1, reaction temperature 180 ℃, reaction time of 60min. The degradation rate of microcrystalline cellulose was 61.15%., the total reducing sugar yield was 88.78%, while the main by-product of cellulose degradation were produced such as furfural, 5-HMF, levulinic acid, formic acid and acetic acid. The results can provide reference and data for future research.

Key words: Microcrystalline cellulose; Polar aprotic solvent; Degradation; Acetone

目 录

摘要 Ⅰ

ABSTRACT Ⅱ

第一章 文献综述 1

1.1生物质能资源 1

1.1.1 能源与环境问题 1

1.1.2 研究生物质能的意义 1

1.1.3 纤维素降解机理 1

1.2常见的纤维素水解方法与优劣性 1

1.2.1 无机酸水解 1

1.2.2 有机酸水解 2

1.2.3 酶催化降解 2

1.2.4 离子溶液降解 2

1.3 质子酸作催化剂降解纤维素 3

1.4 纤维素降解的溶剂体系 3

1.5 本课题研究意义和研究内容 4

第二章 实验方法与器材 5

2.1实验材料 5

2.1.1 原料 5

2.1.2 试剂 5

2.2实验仪器 6

2.3实验方法及主要流程 7

2.3.1反应温度对微晶纤维素水解性能的影响 7

2.3.2反应时间对微晶纤维素水解性能的影响 7

2.3.3硫酸浓度对微晶纤维素水解性能的影响 8

2.3.4丙酮浓度对微晶纤维素水解性能的影响 8

2.3.5液固比对微晶纤维素水解性能的影响 8

2.3.6不同有机溶剂对微晶纤维素水解性能的影响.....................................8

2.3.7检测方法 8

第三章 结果与讨论 10

3.1反应温度对微晶纤维素水解性能的影响 10

3.2反应时间对微晶纤维素水解性能的影响 11

3.3硫酸浓度对微晶纤维素水解性能的影响 12

3.4丙酮浓度对微晶纤维素水解性能的影响 13

3.5液固比对微晶纤维素水解性能的影响 14

3.6不同有机溶剂对微晶纤维素水解性能的影响 15

第四章 结论与展望 16

4.1 结论 16

4.2 展望 17

参考文献 18

致 谢 21

第一章 文 献 综 述

1.1生物质能资源

1.1.1资源与环境问题

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