酶法木质素的活化-氧化及制备芳香醛的研究

摘要：随着人们环保意识的逐渐加强，将我们生活中的的一些废弃物变废为宝成为当今的研究热点。秸秆作为一种种植废料，分布广、数量大，而且被大量焚烧，造成极大的资源浪费和严重的环境污染。秸秆木质素含量高，利用木质纤维原料可以制备多种高附加值的产品，酶法木质素由于初始反应条件温和，保留了天然木质素的很多功能团，如酚羟基、醇羟基和甲氧基等，杂质含量低，分子量分布窄，可用于合成木质素基小分子化合物——芳香醛化合物。本论文采用两步高级氧化反应使木质素降解产生芳香醛化合物：第一步采用fenton试剂对酶解木质素进行活化，第二步采用催化湿式氧化法（CWO法）即碱性条件下催化氧化木质素降解产生芳香醛类化合物，以提高芳香醛化合物的转化率。通过论文的实施，初步建立活化-氧化两步反应体系及氧化效果的表征方法。并发现通过fenton试剂处理后的木质素转化率最高，同时损失率也最高。而只通过H2O2处理，转化率和通过fenton试剂处理差不多，但损失率较小，可以作为合适的工艺路径。67017

毕业论文关键词：秸秆，木质素，Fenton试剂，对羟基苯甲醛，丁香醛，香草醛

Abstract: With the growing concerns about environmental pollution and unsustainable development of our society, the search for renewable alternative resources is critically important. Biomass can serve as a sustainable source of renewable fuels and chemicals to meet the growing demand for energy due to the particularity of its chemical structure. A great deal of residue containing a lot of lignin produced from the saccharification process of biomass is both a huge waste of resource and a cause of environmental pollution. The principal objective of this study was to investigate the possibility of utilizing Fenton reagent with high oxidation electrode potential of hydroxyl radicals HO· as activator in the process of lignin degradation for the preparation of aromatic aldehydes and to obtain optimum conditions. Activation process by H2O2 or Fenton’s reagent was adopted to promote the catalyzed oxidative degradation process of lignin. It was also observed that the highest yield of aromatic aldehyde was obtained by pretreatment with Fenton’s reagent, while the loss ratio of lignin was also the greatest. Pretreatment only with H2O2 lead to acceptable yield of aromatic aldehyde and loss ratio of lignin which could be considered to be the optimum pretreatment process.

Keywords: Straw, lignin, Fenton’s reagent, p-Hydroxybenzaldehyde, 3,5-Dimethoxy-4- hydroxybenzaldehyde, vanillin

1 绪论 4

1.1 选题背景和意义 4

1.2 木质素 4

1.2.1 Fenton试剂 4

2 实验材料与方法 6

2.1 实验材料及实验设备 6

2.2 实验方法 6

2.2.1 原料制备 6

2.2.2 原料活化 7

2.2.3 催化氧化 7

2.3.4 中和与检测 8

2.3 数据汇总 8

2.3.1 生成物分析 8

2.3.2 生成物质量总汇 16

2.3.3 结果探讨 17

结论 20

参考文献 21

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