Lignin is a biopolymer generated from the pulp and paper industry as a natural resource. Lignin valorization is advantageous for biorefineries to produce aromatic compounds, fragrance, biofuel, material, and commodity chemicals, which could be an alternative of crude oil-derived products. However, several barriers are involved in natural lignin extraction and depolymerization, which need to be solved for its full utilization. The electrochemical oxidative upgrading of lignin into the oxygenated molecule is a promising method, which cleaves the C–O and C–C bond by direct oxidative or indirect oxidative method. As promising solvents, electrolytes, as well as catalysts in organic synthesis and electrochemical processes, ionic liquids (ILs) and deep eutectic solvents (DESs) have gained significant attention as dissolution media and catalysts for lignin depolymerization. In this work, aromatic carbon-rich lignin macromolecule depolymerization in ILs/DESs was reviewed to gain a better understanding of barriers, covering the interaction of ILs/DESs with lignin structure, degradation mechanism, thermochemical and electrochemical transformations, as well as COSMO-RS theoretical modeling and screening. In-situ generation of free radicals as catalysts (reactive oxygen species or HO) for lignin degradation into value-added products was also discussed. All these studies give importance to ILs/DESs for thermochemical, electrochemical lignin cleavage and upgrading to value-added products for achieving sustainable future goals.

中文翻译：

---

深入了解离子液体和低共熔溶剂中的木质素氧化解聚


木质素是作为自然资源从纸浆和造纸工业中产生的生物聚合物。木质素增值有利于生物精炼厂生产芳香族化合物、香料、生物燃料、材料和商品化学品，这些可以成为原油衍生产品的替代品。然而，天然木质素的提取和解聚存在一些障碍，需要解决这些障碍才能充分利用。将木质素电化学氧化升级为含氧分子是一种很有前景的方法，它通过直接氧化或间接氧化的方法裂解C-O和C-C键。作为有机合成和电化学过程中有前途的溶剂、电解质以及催化剂，离子液体（IL）和低共熔溶剂（DES）作为木质素解聚的溶解介质和催化剂而受到广泛关注。在这项工作中，回顾了ILs/DESs中芳香碳富集的木质素大分子的解聚，以更好地了解障碍，涵盖ILs/DESs与木质素结构、降解机制、热化学和电化学转化以及COSMO-RS的相互作用。理论建模和筛选。还讨论了原位产生自由基作为木质素降解成增值产品的催化剂（活性氧或 H2O）。所有这些研究都重视 IL/DES 用于热化学、电化学木质素裂解和升级为增值产品，以实现可持续的未来目标。