Lignin—an underutilized component of lignocellulosic biomass and an aromatic polymer has an immense potential for the production of valuable chemicals. The ultimate goal of our research is to understand the lignin depolymerization at a lower temperature to obtain valuable chemicals such as vanillin, phenol-2-methoxy in the absence of a solid catalyst. Alkali lignin was depolymerized using polar protic solvents such as methanol, ethanol, and water and with co-solvents methanol-water, ethanol-water, and methanol-ethanol system at 120 °C under nitrogen (N₂) and hydrogen (H₂) and reaction pressure (1, 5, 10, 15, and 20 bar). The results show that efficient depolymerization can be achieved in an ethanol-water (50/50, W/W) co-solvent system under an N₂ environment. The use of H₂ enhanced lignin depolymerization and maximum bio-oil yield (51.6 wt.%) was observed under 10 bar H₂ pressure with an ethanol-water solvent system. The bio-oil was analyzed using GC-MS, FT-IR, and ¹H-NMR. The bio-oil compounds identified from GC-MS analysis were classified into G, H, and other type compounds. Interestingly, higher selectivity (90.77%) of G-type compounds was found in lignin depolymerized bio-oil with a high yield of vanillin. The reaction mechanisms showed that functional compounds are produced from the cleavage of ether C-O (β-O-4) type and C-C (5-5) type bonds.

木质素-木质纤维素生物质的一种未被充分利用的成分和一种芳香族聚合物，在生产有价值的化学药品方面具有巨大的潜力。我们研究的最终目的是了解木质素在较低温度下的解聚反应，从而在没有固体催化剂的情况下获得有价值的化学物质，如香兰素，苯酚-2-甲氧基。使用极性质子溶剂（例如甲醇，乙醇和水）并与助溶剂甲醇-水，乙醇-水和甲醇-乙醇体系在120°C下在氮气（N ₂）和氢气（H ₂）下解聚碱性木质素和反应压力（1、5、10、15和20 bar）。结果表明，在N ₂下，在乙醇-水（50/50，W / W）共溶剂体系中可以实现有效的解聚环境。在乙醇-水溶剂体系下，在10 bar H ₂压力下，观察到H ₂增强的木质素解聚作用和最大生物油产率（51.6 wt。％）。使用GC-MS，FT-IR和¹ H-NMR分析生物油。通过GC-MS分析鉴定出的生物油化合物分为G，H和其他类型的化合物。有趣的是，在木质素解聚的生物油中，以香草醛的高收率发现了G型化合物的更高选择性（90.77％）。反应机理表明，官能化合物是由醚CO（β-O-4）型和CC（5-5）型键的裂解产生的。