生物大分子的解聚研究

邱学青

摘 要：为了充分研究生物质大分子的解聚机理，课题组对纤维素水解的关键影响因素、纤维素、半纤维素水解机理、木质素解聚方式和表征、木质素模型化合物的制备等关键科学问题进行了探讨。借助SEM、BET、XRD研究手段，研究了半纤维素的水解、纤维素的结晶度、聚合度对对纤维素水解的影响规律；借助TEM、EDXA-SEM和Raman等分析手段，从超微尺度入手，追踪解聚过程中木质素、半纤维素和纤维素在细胞壁中的分布变化。结果表明，半纤维素被水解移除后，生物质表面孔洞增多，孔隙率、总孔容增大，从而促进了纤维素的水解；相比于聚合度而言，晶型结构对水解的影响更大。在酸性环境下，木质素在细胞壁各层间发生迁移，而在碱性环境中木质素会直接脱除。同时，该课题开展了在微波协同下的木质素催化氧化解聚及液化解聚，并通过比较了不同的氧化剂的种类对解聚产物单苯环物质收率的影响，并通过液质联用，高压液相色谱等手段对解聚产物进行定性和定量分析。结果表明，微波协同下在相对较低的温度和压力下获得单苯环化合物的收率可达到15.2%。为了对木质素的解聚机理进行进一步的研究，该课题合成了包含α-o-4，β-o-4和β-5键的木质素模型物三聚体和四聚体，并通过气质联用色谱和核磁共振色谱等手段进行分析和表征。木质素模型物的合成为后续的木质素解聚机理奠定基础，并为木质素解聚为单酚类化合物的高收率目标提供参考。

关键词：解聚机理 纤维素 木质素 模型物

Abstract：For the purpose of investigation of the depolymerization mechanism of biomass macromolecule，some key scientific issues were explored，including important factors responsible for the hydrolysis of cellulose，depolymerization mechanism of hemicelluloses and cellulose，characterization of degraded products of lignin，and preparation of model compounds of lignin.The distribution of lignin， hemicellulose and cellulose in the cell walls was traced from the perspective of superfine scale in the process of depolymerization by using TEM， EDXA-SEM and Raman spectroscopy. In addition， the effect of hemicelluloses hydrolysis， degree of crystallization and polymerization on the hydrolysis of cellulose was investigated by using SEM， BET， and XRD. The result revealed that lignin was migrated in the cell walls between the layers in the acidic condition and lignin was removed directly in alkaline environment. For further inspection， the dynamics of alkali treatment to dissolve the lignin were investigated. In the meanwhile， oxidation degradation and liquefaction depolymerization of lignin were carried out assisted with microwave irradiation. And then the different kinds of oxidants on the influence of the yield of the product were studied. Qualitative and quantitative analysis of the product were characterized by LC-MS and HPLC.For further study of the rule of lignin deploymerization， several lignin model compounds composed of α-o-4，β-o-4 and β-5 linkages were synthesized. The target products were characterized by GC-MS and NMR spectroscopy. The lignin model compounds laid the foundation for the subsequent study of the mechanism of lignin deploymerization and provided the reference to achieve high yield of phenolic compounds through the degradation of lignin model compounds.

Key Words：Deploymerization mechanism；Cellulose；Lignin；Model compounds

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