Oxidative depolymerization of lignin improved by enzymolysis pretreatment with laccase

A new lignin depolymerization approach for improving the yield of aromatic monomers（YAM） by enzymolysis pretreatment was investigated, in which lignin was pretreated with laccase followed by oxidative depolymerization. It was found that lignin depolymeirzation was enhanced significantly by enzymolysis. The oxidative depolymerization contributed to 21.37% of YAM after the enzymolysis pretreatment,whereas the conventional oxidative depolymerization only gave 14.10% of YAM. The addition of ethanol in enzymatic pretreatment process improved the efficiency of enzymolysis, which effectively improved the solubility of pretreated lignin and depolymerization degree（DD） of lignin. The enzymolysis pretreatment increased the content of syringyl（S） style aromatic monomers, which hindered the recondensation among polymerized products. As lignin has low solubility in acidic aqueous solution, ethanol was added into enzymolysis system to improve the efficiency. However, the enzymolysis of lignin should be carried out for a limited period of time to prevent the inactivation of laccase.

木质素液相催化解聚研究现状

木质素是一种天然非晶三维聚合物,是木质纤维素类生物质的主要组分。木质素结构中含有丰富的芳香结构以及甲氧基、酚羟基、醇羟基、羰基、醛基等官能团,是自然界中唯一具备芳香族单体的可再生资源。将木质素转化为具有高附加值的液体燃料和化学品是缓解化石资源危机的有效途径。然而,由于结构复杂,木质素是生物质三大组分中最难以被高值化利用的组分。木质素液相催化解聚在液相环境中进行,反应条件较温和,产物选择性高,因而受到广泛关注。基于木质素结构,综述国内外木质素液相催化解聚研究进展,在此基础上,对其存在问题和解决方法进行了合理分析,并指出未来发展方向。