School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou 510640, P. R. China.
Guangdong Provincial Key Lab of Green Chemical Product Technology, Guangzhou 510640, P. R. China.
J Agric Food Chem. 2021 Sep 22;69(37):10838-10847. doi: 10.1021/acs.jafc.1c03774. Epub 2021 Sep 13.
The traditional pretreatment leads to the recalcitration of C-C bonds during lignin fractionation, thus hindering their depolymerization into aromatic monomers. It is essential to develop an applicable approach to extract noncondensed lignin for its high-value applications. In this work, noncondensed lignins were extracted from poplar sawdust using recyclable -toluenesulfonic acid for cleaving lignin-carbohydrate complex bonds effectively and ethanol as a stabilization reagent to inhibit lignin condensation. Lignin yield of 83.74% was recovered by 3 mol/L acid in ethanol at 85 °C for 5 h, and carbohydrates were well preserved (retaining 98.97% cellulose and 50.01% hemicelluloses). During lignin fractionation, the acid concentration and extraction time were the major drivers of condensation. Ethanol reacted with lignin at the α-position to prevent the formation of the condensed structure. The extracted lignin depolymerized over the Pd/C catalysts gave a yield of 50.35% of aromatic monomers, suggesting that the novel extraction process provided a promising way for noncondensed lignin production.
传统的预处理方法会导致木质素分馏过程中 C-C 键的顽固性，从而阻碍其解聚为芳香单体。因此，开发一种适用于提取非缩合木质素的方法对于其高价值应用至关重要。在这项工作中，使用可回收的对甲苯磺酸从杨木屑中有效地提取非缩合木质素，以裂解木质素-碳水化合物复合键，并用乙醇作为稳定试剂来抑制木质素缩合。在 85°C 下，用 3mol/L 的酸在乙醇中反应 5 小时，可回收 83.74%的木质素产率，并且碳水化合物得到了很好的保留（纤维素保留 98.97%，半纤维素保留 50.01%）。在木质素分级过程中，酸浓度和提取时间是缩合的主要驱动因素。乙醇与木质素在α-位反应，以防止缩合结构的形成。在 Pd/C 催化剂的作用下，提取的木质素解聚生成芳香单体的产率为 50.35%，这表明该新型提取工艺为非缩合木质素的生产提供了一种有前途的方法。
