Joint BioEnergy Institute, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Emeryville, CA, United States.
Bioresour Technol. 2012 Dec;126:156-61. doi: 10.1016/j.biortech.2012.08.070. Epub 2012 Aug 31.
Ionic liquids (ILs) have shown great potential for the reduction of lignin in biomass after pretreatment. Although dilute acid and base pretreatments have been shown to result in pretreated biomass with substantially different lignin composition, there is scarce information on the composition of lignin of IL pretreated biomass. In this work, temperature dependent compositional changes in lignin after IL pretreatment were studied to develop a mechanistic understanding of the process. Panicum virgatum and Eucalyptus globulus were pretreated with 1-ethyl-3-methylimidazolium acetate ([C(2)mim][OAc]). Measurement of syringyl and guaiacyl ratio using pyrolysis-GC/MS and Kamlet-Taft properties of [C(2)mim][OAc] at 120 °C and 160 °C strongly suggest two different modes of IL pretreatment. Preferential breakdown of S-lignin in both eucalyptus and switchgrass at high pretreatment temperature (160 °C) and breakdown of G-lignin for eucalyptus and no preferential break down of either S- or G-lignin in switchgrass was observed at lower pretreatment temperatures (120 °C).
离子液体 (ILs) 在预处理后对生物质中木质素的还原显示出巨大的潜力。尽管稀酸和碱预处理已被证明会导致预处理生物质的木质素组成有很大差异，但关于 IL 预处理生物质木质素组成的信息却很少。在这项工作中，研究了 IL 预处理后木质素的组成随温度的变化，以深入了解该过程的机理。采用 1-乙基-3-甲基咪唑醋酸盐 ([C(2)mim][OAc]) 对柳枝稷和桉树进行预处理。使用热解-GC/MS 测量愈创木基和紫丁香基比率，以及在 120°C 和 160°C 下 [C(2)mim][OAc] 的 Kamlet-Taft 性质，强烈表明存在两种不同的 IL 预处理模式。在较高预处理温度 (160°C) 下，桉树和柳枝稷中的 S-木质素优先断裂，而在较低预处理温度 (120°C) 下，桉树中的 G-木质素断裂，而柳枝稷中 S-或 G-木质素均无优先断裂。
