内蒙五牧场矿区11号煤层原煤大分子结构特征及其形成机制

Macromolecular structure and formation mechanism of raw coal in coal seam 11 of Wumuchang district,Inner Mongolia

在对内蒙古自治区呼伦贝尔市伊敏盆地五牧场区11号煤层原煤工业分析、元素分析、13C-NMR、FT-IR、XPS等分析基础上,获得了煤大分子结构中碳骨架信息、脂肪结构以及含氧官能团类型及比例、氮原子的存在形式和比例等结构信息。以此为基础,构建了煤的大分子结构模型,并应用13C-NMR预测软件ACD/CNMR predictor对其进行了修正,获得与实验核磁共振谱图吻合较好的大分子结构模型。大分子结构的芳香结构单元以苯、萘、蒽、菲为芳香结构单元,数量分别是1、2、2、1,醚键、氢化芳环以及邻位亚甲基作为连接芳香结构的主要桥键;氧原子以酚羟基、羰基、羧基的形式存在,数量分别是7、3、2;氮原子分别以吡啶和吡咯的形式存在,甲基和脂肪短链分布在芳香单元的边缘。与相邻矿区的褐煤及相近变质程度的神东长焰煤的比较发现,其形成机制主要是在高温低压环境下,热演化过程中快速失去各种含氧官能团,导致短链脂肪类物质的形成,而低压环境则有利于热演化过程中形成的各种小分子物质逸散导致自由基的缩聚,形成较大的芳香结构单元,但是直链脂肪类物质的存在具有位阻效应,不利于芳香结构单元的定向排列,导致所谓的"化学成分成熟超前于其结构成熟"现象。

Based on the results of proximate analysis, elemental analysis, 13C-N/VIR, FT-IR and XPS results, the structure model of the raw coal in coal seam 11 of Wumuchang district, Yimin Basin of Hulun Buir, Inner Mongolia was built using ACD/lab software. The 13C-NMR predicting software ACD/CNMR predictor was used to modify the structure. The macromolecule structure model which coincides with the nuclear magnetic resonance map is achieved. The characteristics of structures of macromolecules are as follows. Benzene, naphthalene, anthracene and phenanthrene are aromatic constitutional units, the quantities are 1, 2, 2, 1 respectively. Ether linkages, hydrogen aromatic rings and ortho methylene are bridges connecting aromatic units. Oxygen atoms exist in forms of phenolic hydroxyl groups, the quantities are 7, 3, 2 respectively. Nitrogen atoms exist in forms of pyridine and pyrrole. Methyl and short fatty chains are distributed in the edges of aromatic rings. The coal structure is compared with lignite in nearby mining area and Shendong long flame coal with similar metamorphic grade. In the environment of high temperature and low pressure, oxygen containing functional groups are lost rapidly in the process of thermal revolution, leading to the formation of short chain aliphatic groups. The environment of low pressure during thermal revolution is benefit with escape of micro molecules, leading to the aggregation of free radicals, so that large aromatic structure units are formed. However, due to the steric effect caused by the linear chain aliphatic groups, the orientation arrangement of aromatic structure units is not favored, leading to the phenomenon that the maturation of chemical components occurs before that of coal structure.