Experimental and Theoretical Studies on the Pyrolysis Mechanism of β-1-Type Lignin Dimer Model Compound
Experimental and Theoretical Studies on the Pyrolysis Mechanism of β-1-Type Lignin Dimer Model Compound
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DOI：
10.15376/biores.11.3.6232-6243
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发表时间：
2016-08-01
期刊：
影响因子：
1.5
通讯作者：
Dong, Chang-Qing
中科院分区：
文献类型：
--
作者：
Jiang, Xiao-Yan;Lu, Qiang;Dong, Chang-Qing
本研究以β-1型木质素二聚体1，2-双(3，5-二甲氧基苯基)丙烷-1，3-二醇为模型化合物。用密度泛函理论(DFT)计算和分析裂解气相色谱/质谱仪(Py-GC/MS)研究了热解机理和热解产物的生成途径。提出了四种可能的初始热解机理，包括C-α-C-β均解机理和三种协同分解机理(1、2和3)。结果表明，木素二聚体通过两种协同分解机制分解，生成3，5-二甲氧基苯甲醛、1，3-dimethoxy-5-vinylbenzene，3-hydroxy-5-methoxybenzaldehyde，和3-甲氧基苯甲醛。热解产物以3，5-二甲氧基苯甲醛为主，占全部热解产物的50%以上。在木质素二聚体的热解过程中，除两种协同分解机理外，C-α-C-β均裂为二次裂解机理，热解产物包括3，5-二甲氧基苯甲醇、3，5-二甲氧基苯乙醇、1，3-二甲氧基苯和1，3-二甲氧基-5-甲苯。第三种协同分解机制被认为是最不可能发生的途径，因为需要较高的活化能。
A beta-1-type lignin dimer, 1,2-bis(3,5-dimethoxyphenyl)propane-1,3-diol was employed as a model compound in this study. The pyrolysis mechanisms and formation pathways of the pyrolytic products were investigated by using density functional theory (DFT) calculations and analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Four possible initial pyrolysis mechanisms were proposed, including the C-alpha-C-beta homolysis mechanism and three concerted decomposition mechanisms (1, 2, and 3). Results indicated that the lignin dimer decomposed via two concerted decomposition mechanisms, forming 3,5-dimethoxybenzaldehyde, 1,3-dimethoxy-5-vinylbenzene,3-hydroxy-5-methoxybenzaldehyde,and 3-methoxybenzaldehyde. 3,5-Dimethoxybenzaldehyde was the major product, accounting for greater than 50% of all pyrolytic products. In addition to the two concerted decomposition mechanisms, C-alpha-C-beta homolysis was a secondary pyrolysis mechanism during the lignin dimer pyrolysis process, and the pyrolytic products included 3,5-dimethoxybenzyl alcohol, 3,5-dimethoxyphenethyl alcohol, 1,3-dimethoxybenzene, and 1,3-dimethoxy-5-methylbenzene. A third concerted decomposition mechanism was judged to be the least likely pathway to occur because of the high activation energy requirement.