褐煤表面官能团的分布特征及量子化学分析

Distribution and quantum chemical analysis of lignite surface functional groups

为了揭示煤中官能团活性大小顺序,采用原位傅里叶红外光谱法对北皂褐煤进行漫反射测试,分析了褐煤中各官能团的分布比例.基于各官能团同等构连条件建立了褐煤的红外简化化学结构模型,并对模型进行了量子化学分析.煤中主要活性官能团以甲基亚甲基和羟基最多,其次是羰基、羧基和芳烃上的碳氢键.通过模型的振动频率和前沿轨道分析,得出实验和计算结果所示各官能团振动位置相一致.结合各官能团含量和活性大小可知,煤自燃过程中关键性的官能团是羟基和甲基亚甲基基团,其次是羧基.

In order to reveal the sequence of active functional groups, diffuse reflectance tests of Beizao lignite were carried out by in situ Fourier infrared spectrometry, and the proportions of active functional groups in the lignite were obtained. A simplified infrared molecular model of the lignite was built based on the same articulation condition of functional groups, and the model was analyzed by using the quantum chemical method. For the main active functional groups, the pr_oportions of methyl methylene and hydroxyl groups are the largest, followed by carbonyl, carboxyl and aromatic hydrocarbon. The frontier orbital and vibration frequency analysis of the model shows that the vibration locations of functional groups in the experiments are consistent with the calculated ones. Combined with the proportions of functional groups and the activity, it can be concluded that in spontaneous combustion the key functional groups are hydroxyl groups and methyl methylene, and then carboxyl.