College of Metrology and Measurement Engineering, China Jiliang University, Hangzhou 310096, China.
Jiangsu Frontier Electric Power Technology Co., Ltd., Nanjing 211102, China.
Int J Mol Sci. 2017 Oct 1;18(10):2082. doi: 10.3390/ijms18102082.
Microwave-assisted depolymerization of black-liquor lignin in formic acid was studied, concentrating on the yield of liquid fractions as bio-oil 1 (mainly aromatic monomers) and bio-oil 2 (mainly aromatic oligomers) and the distribution of the specific compositions. Bio-oil 1 (9.69%) and bio-oil 2 (54.39%) achieved their maximum yields under 160 °C with the reaction time of 30 min. The chemical compositions of bio-oil 1 and bio-oil 2 were respectively identified by means of Gas Chromatography-Mass Spectrometer (GC-MS) and Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Ethanone, 1-(4-hydroxy-3-methoxyphenyl) and Ethanone, 1-(4-hydrox-3,5-dimethoxyphenyl) were evidenced to be the two prominent compounds in bio-oil 1. Production of aromatic oligomers with the molecular weight of 328, 342, 358, 378, 394, 424 and 454 identified by MALDI-TOF MS was substantially tuned with the reaction temperature. A two-separate-stage kinetic model was proposed to describe the acidic solvolysis of lignin assisted by microwave heating, where the first stage is dominated by the depolyerization of lignin to monomers and oligomers with the activation energy of 40.27 kJ·mol, and the second stage with the activation energy of 49.18 kJ·mol is mainly ascribed to the repolymerization of first-stage produced compounds.
研究了微波辅助甲酸解聚黑液木质素，重点关注液体馏分（主要为芳香族单体）和生物油 2（主要为芳香族低聚物）的产率以及特定成分的分布。在 160°C 下反应 30 分钟，生物油 1（9.69%）和生物油 2（54.39%）达到最大产率。通过气相色谱-质谱联用仪（GC-MS）和基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）分别鉴定了生物油 1 和生物油 2 的化学成分。结果表明，生物油 1 中的两种主要化合物为 1-（4-羟基-3-甲氧基苯基）-乙酮和 1-（4-羟基-3,5-二甲氧基苯基）-乙酮。通过 MALDI-TOF MS 鉴定出分子量为 328、342、358、378、394、424 和 454 的芳香族低聚物的产量与反应温度密切相关。提出了一个两阶段动力学模型来描述微波加热辅助下木质素的酸性解聚反应，其中第一阶段主要由木质素解聚为单体和低聚物，其活化能为 40.27 kJ·mol，第二阶段的活化能为 49.18 kJ·mol，主要归因于第一阶段产生的化合物的重聚。
