Power China Northwest Engineering Corporation Limited
National Engineering ResearchCenter of New Energy Power Generation, North China Electric Power University

木质素是由苯基丙烷结构通过C—O键和C—C键连接而成的复杂三维网状无定形高聚物,热解是木质素的重要利用方式,探究木质素热解过程中连接键的断裂机理对于开发高效热解技术至关重要。利用密度泛函理论方法,针对典型的β-5连接木质素二聚体模型化合物,探究其热解过程及取代基的影响。计算结果表明,苯环之间五元环的开环反应是最可能发生的初步反应,其中Cα—O键和Cα—Cβ键的键解离能(BDEs)分别为163.9kJ/mol和212.9kJ/mol,是最主要的断键开环反应。通过对比甲基、甲氧基、羟基、正丙基等支链对β-5连接键的断裂的影响,发现当两个苯环和β-5连接五元环上分别连接羟基、丙基、羟甲基取代基时,Cα—O键和Cα—Cβ键的BDEs最低。对于不同取代基类型和位点来说,Cα—O键均裂始终是最容易发生的初始反应,而Cα—O键和Cα—Cβ键连续断裂的路径是β-5连接五元环断裂的主要途径。

Lignin is a highly complex amorphous three -dimensional network polymer connected byC—O bond and C—C bond. Understanding the bond cleavage mechanism during lignin pyrolysis is crucial for advancing efficient pyrolysis technology, as it serves as a significant avenue to harness lignin′spotential. In this paper, the density functional theory method was employed to investigate the process of alignin dimer model compound that contains β -5 linkages. The calculation results show that the mostlikely initial reaction is the five-membered ring-opening reaction between benzene rings, in which thebond dissociation energies (BDEs) of the Cα—O bond and Cα—Cβ bond are 163.9 kJ/ mol and 212.9kJ/ mol , respectively. These reactions are the main ring-opening reactions. By comparing the cleavage ofβ-5 linkages among the dimers that carry methyl, methoxy, hydroxyl, n-propyl, and other branchedchains, it is found that the BDEs of the Cα—O bond and Cα—Cβ bond are at a minimum when hydroxyl,propyl, and hydroxymethyl groups are attached to the two benzene rings and the five-membered ring, respectively. Homolytic cleavage of the Cα—O bond is always the initial reaction, and the continuous fracture of the Cα—O and Cα—Cβ bonds is the main path to break the five-membered ring.

国家自然科学基金资助项目(52106241,52276189);“西安英才计划”青年人才资助项目(XAYCQN21002)

李文涛,高丽娟,周关正,等.β-5型木质素二聚体热解机理模拟计算[J].能源环境保护,2024,38(2):208-214.

LI Wentao, GAO Lijuan, ZHOU Guanzheng, et al. Computational study on pyrolysis mechanism of β-5 linkedlignin dimers[J]. Energy Environmental Protection, 2024, 38(2): 208-214.