Abstract：
Converting lignin into aromatic chemicals is a promising strategy for the high-value utilization of lignocellulosic feedstock. However, the inherent heterogeneity of lignin poses a significant obstacle to achieving efficient conversion and optimal product yields within bio-refinery systems. Herein, we employed a one-step fractionation method to enhance lignin homogeneity and utilized the THF/DMSO-EtONa (tetrahydrofuran/dimethyl sulfoxide-sodium ethoxide) system to depolymerize the fractionated lignin. Three protic and three aprotic solvents were used for fractionation. The impact of the solvent properties on the structure and the depolymerization efficiency of the fractionated lignin was investigated. Methanol-fractionated lignin generated the benzoic acid compounds with a yield of 30 wt%, 50 % higher than that of the unfractionated lignin. The polarities (δP), hydrogen bonding abilities (δH), and viscosities (η) of selected protic solvents showed strong linear correlation with molecular weight (Mw), polymer dispersity index (PDI), and syringyl/guaiacyl ratio (S/G ratio) of the fractionated lignin, as well as the total yield of benzoic acid compounds derived from the β-O-4 bond cleavage. This study elucidates the relationship between solvent properties and lignin structure and proposes a promising approach for refining lignin to enhance utilization efficiency, thereby presenting a potential strategy for value-added application of complex lignin polymers.
摘要：
将木质素转化为芳香化学品是一种高价值利用木质纤维素原料的有前途的策略。然而,木质素的固有异质性对在生物精炼系统中实现有效转化和最佳产品产量构成了重大障碍。在这里，我们采用一步分级分离方法来增强木质素的均匀性，并利用THF/DMSO-EtONa（四氢呋喃/二甲基亚砜-乙醇钠）系统来解聚分馏的木质素。使用三种质子溶剂和三种非质子溶剂进行分馏。研究了溶剂性质对分馏木质素的结构和解聚效率的影响。甲醇分馏木质素产生的苯甲酸化合物的产率为30重量%，比未分馏的木质素高50%。极性（δP），氢键能力（δH），选择的质子溶剂的粘度（η）与分子量（Mw）表现出强的线性相关，聚合物分散指数(PDI)，和分级分离的木质素的丁香基/愈创酰基比（S/G比），以及由β-O-4键断裂衍生的苯甲酸化合物的总产率。这项研究阐明了溶剂性质与木质素结构之间的关系，并提出了一种有希望的方法来精炼木质素以提高利用效率，从而提出了复杂木质素聚合物增值应用的潜在策略。
