Theoretical Study on the Kinetics of Thermal Decomposition of Guaiacol and Catechol
Theoretical Study on the Kinetics of Thermal Decomposition of Guaiacol and Catechol
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DOI：
10.1021/acs.jpca.7b08112
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发表时间：
2017-11-09
影响因子：
2.9
通讯作者：
Norinaga, Koyo
中科院分区：
文献类型：
--
作者：
Furutani, Yuki;Dohara, Yuki;Norinaga, Koyo
提出了愈创木酚和邻苯二酚热解化学动力学模型的理论方面，以描述单个木质素衍生组分的热解行为。在CBS-QB 3水平上计算了反应的势能面，研究了单分子和双分子裂解的可能途径。基于过渡态理论（TST）计算了各基元反应步骤的高压极限速率常数，确定了主要的热解途径。动力学分析结果预测了最有利的儿茶酚单分子分解途径，其中儿茶酚异构化为2-羟基环己-2，4-二烯-1-酮通过羟基H原子的迁移发生，然后分解为1，3-环丁二烯，乙炔和CO。在儿茶酚的双分子反应的情况下，氢自由基与苯环上的碳原子偶联，导致通过脱羟基形成苯酚和羟基自由基。另一方面，愈创木酚可能分别通过O-CH 3均裂和氢自由基与具有甲氧基的碳原子的偶联形成邻苯二酚和苯酚。
The theoretical aspects of the development of a chemical kinetic model for guaiacol and catechol pyrolysis are presented to describe the pyrolysis behaviors of the individual lignin-derived components. The possible pyrolysis pathways involving both unimolecular and bimolecular decomposition were investigated by the potential energy surfaces (PES) calculated at CBS-QB3 level. The high-pressure limiting rate constants of each elementary reaction step were evaluated based on the transition state theory (TST) to determine the dominant pyrolysis pathways. The kinetic analysis results predicted the most favorable catechol unimolecular decomposition pathways, where catechol isomerization to 2-hydroxycyclohexa-2,4-dien-1-one occurred via migration of the hydroxyl H atom, followed by decomposition into 1,3-cyclobutadiene, acetylene, and CO. In the case of the bimolecular reaction of catechol, a hydrogen radical is coupled to the carbon atom in the benzene ring, leading to the formation of phenol and a hydroxyl radical through dehydroxylation. On the other hand, guaiacol is likely to form catechol and phenol via the O-CH3 homolysis and coupling of a hydrogen radical to the carbon atom with the methoxyl group, respectively.