| β-O-4型木质素二聚体热解历程的密度泛函理论研究 |
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| 引用本文： | 蒋晓燕,陆强,董晓晨,胡斌,董长青.β-O-4型木质素二聚体热解历程的密度泛函理论研究[J].林产化学与工业,2016(1):20-26. |
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| 作者姓名： | 蒋晓燕 陆强 董晓晨 胡斌 董长青 |
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| 作者单位： | 华北电力大学 可再生能源学院 生物质发电成套设备国家工程实验室,北京,102206 |
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| 基金项目： | 国家火炬计划项目(2013GH561645)，国家自然科学基金资助项目(51276062) |
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| 摘 要： | 为了解木质素的热解机理,利用密度泛函理论B3LYP方法,在6-31++G(d,p)基组水平上对含有C_α位羰基的β-O-4型木质素二聚体模型化合物(3-羟基-1-(4-羟基苯基)-2-苯氧基-1-丙酮)的热解过程进行了理论计算和分析。结果表明,C_α位上的羰基取代基可大大降低C_β—O的键解离能,提高C_α—C_β的键解离能,使得C_β—O的键解离能比C_α—C_β低91.5 k J/mol,因此该二聚体主要通过C_β—O键均裂的方式发生热解反应,其主要酚类热解产物是苯酚和4-羟基苯甲醛,次要产物是4-羟基苯乙酮,生成4-羟基苯甲醛的动力学最优路径是R7-a,其反应能垒为236.6 k J/mol。
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| 关 键 词： | 木质素 β-O-4型二聚体 热解机理 密度泛函理论 |
Studies on Pyrolysis Process of β-O-4 Type Lignin Model Dimer Using Density Functional Theory |
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| Abstract: | In order to understand the pyrolysis mechanism of lignin,3-hydroxy-1-(4-hydroxyphenyl)-2-phenoxypropan-1-one with Cα carbonyl group was selected as a β-O-4 type lignin model dimer, and its pyrolysis process was theoretically calculated by density functional theory methods at B3LYP level with 6-31 ++G(d,p) basis set. The calculation results indicated that the carbonyl substituent on the Cα dramatically could significantly decrease the bond dissociation energy ( EBD ) of Cβ—O,while the bond dissociation energy of Cα—Cβ was augmented. The bond dissociation energy of Cβ—O was 91. 5 kJ/mol lower than that of Cα—Cβ. Thus,it could be deduced that the dimer was mainly decomposed through the homolytic cleavage of the Cβ—O linkage,and major phenolic pyrolytic products of phenol and 4-hydroxybenzaldehyde,minor parts of 4-hydroxyacetophenone were formed in this process. The R7-a kinetic way was considered as the optimum way to form 4-hydroxybenzaldehyde,and the energy barrier was 236. 6 kJ/mol. |
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| Keywords: | lignin β-O-4 linkage dimer pyrolysis mechanism density functional theory |
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