煤显微组分分子结构模型的量子化学研究

采用分子力学和半经验量子化学方法，研究了神木煤显微组分的分子结构模型，比较了镜质组和惰质组分子模型的能量构成、不同类型键的键长和键裂解能。研究结果表明，扭转能和范德华能是分子中的主要作用力，取代基对体系能量有明显影响，烷基取代基使体系能量增加，而苯基取代基使体系能量降低；脂肪C—C键长比芳香C—C键长长，说明脂肪C—C在受热过程中比芳香C—C更容易断裂分解。对各键裂解能的计算结果表明，Car—Cal键的裂解能高于Cal—Cal，Car—O醚键的裂解能高于Cal—O醚键。而惰质组结构模型中除C—O醚键外，各键的裂解能均高于镜质组，说明惰质组结构模型比镜质组有较高的热稳定性。

MOLECULAR MODELING OF COAL MACERALS BY USING QUANTUM CHEMISTRY

The molecular modeling of Shenmu coal macerals has been studied and the energy compositions, bond length and bond dissociation energy (BDE) of different types of bonds in the vitrinite and inertinite have been compared by molecular mechanics and semi-empirical calculation method of quantum chemistry. The results show that the torsion energy and van der Waals interaction energy are the main types of energy and the substitution group has a great effect on the total energy of molecular. The aliphatic substitution would lead to the increase of total energy, while the aromatic substitution would lead to the decrease of total energy. The calculated results of bond length show that the bond length of aliphatic C—C is longer than that of aromatic C—C, which indicates that the rupture of aliphatic C—C is easier than that of aromatic C—C on heating. The calculation of BDE shows that the Car—Cal bond has a higher BDE than Cal—Cal, and Car—O bond has a higher BDE than Cal—O bond. And the higher BDE and more aromatic C—C in inertinite structural model than in vitrinite structural model maybe explain the fact that the inertinite has a higher thermal stability than vitrinite.