Abstract:

Lignin can be used to obtain many kinds of fuels, chemicals and materials through rational processing and conversion. Extracting lignin by gentle method is the premise of realizing the high value utilization of lignin. In this paper, the separation methods and research progress of lignin in recent years are reviewed, with emphasis on the separation mechanism of various separation methods and the composition and structure characteristics of lignin. The advantages and disadvantages, applicability and industrial application of different separation methods are summarized. Acid method promotes the hydrolysis of ether bond in polysaccharide polymer to depolymerize hemicellulose and cellulose. Alkali method mainly cracks the ether and ester bond between lignin and carbohydrate. Acid method and alkali method are mature as traditional lignin separation methods, but they are easy to cause the self-polymerization of lignin. Organic solvent method mainly destroys the β-aryl ether bond, and its separation condition is mild, which can better retain the original structure and reactivity of lignin. New green solvent systems such as ionic liquid and deep eutectic solvent have dual functions of solvent and reaction medium, and have received extensive attention. The coupling of separation methods and the assistance of physical, chemical or biological technology will play an important role in optimizing the separation process of lignin and exploring the high-value utilization of lignin.

Key words: lignin, separation methods, structural analysis, separation mechanism

摘要：

木质素经合理加工与转化能获得众多类型的燃料、化学品和材料，利用温和的方法分离木质素是实现其高价值利用的前提。本文综述了近年来木质素的分离方法及研究进展，重点介绍了各种分离方法的分离原理以及所得木质素的组成结构特点，归纳了不同方法的优缺点、适用性以及工业应用情况。酸法促进多糖聚合物中醚键的水解使半纤维素和纤维素解聚，碱法主要裂解木质素与碳水化合物间的醚键和酯键，作为传统木质素分离方法的酸法和碱法较为成熟，但容易引起木质素的自聚；有机溶剂法主要破坏β-芳基醚键，其分离条件较温和，能较好保留木质素的原有结构和反应活性；离子液体和低共熔溶剂等新型绿色溶剂体系具有溶剂和反应介质双重功能，受到了广泛关注。分离方法的耦合与物理、化学、生物技术的辅助将为优化木质素分离过程、探索木质素高值化利用发挥重要作用。

关键词: 木质素, 分离方法, 结构分析, 分离机理