煤自燃实质上是煤中活性基团反应产热并积聚的结果，而煤结构复杂，各种活性基团混杂在一起，现有测试手段难以准确识别煤中参与反应的分子和官能团，从而给煤氧化反应机理的揭示带来巨大的困难。为此，本文基于模型化合物，结合实验测试和量子化学模拟计算，采用活性结构离散化的研究思路，探究了煤中关键活性官能团的氧化反应机理。

      本文选取烟煤为研究对象，测定其碳谱和红外吸收光谱，确定其活性官能团及结构特征参数。结果表明，所选煤样的基本结构单元是萘环，芳香层平均碳原子数是12，关键活性官能团包括羟基（-OH）、芳香醚（Ar-CO）、烷基醚（C-O-C）、羰基（-C=O-）、亚甲基（-CH₂-）、甲基（-CH₃）。以此为基础，采用量子化学模拟软件构建了5种可代表该煤样主要分子结构特征的简易小分子结构模型：苄基苯基醚、二苯基甲烷、萘乙酸、2-甲氧基萘、2-苯基乙醛。依据所建的小分子模型合成了5个类煤模型化合物。

       通过TG/DSC和TG/MS等实验手段，对类煤模型化合物氧化升温中的质量、热量、生成产物等变化情况进行了研究。结果显示，化合物的失重主要是气体的释放所致，且到达一定温度节点时，活性官能团会一直处于活性增强状态，并发生剧烈化学反应，释放出大量指标性气体。化合物在氧化升温过程中产生了多种物质，各物质出现的起始温度点也不同，说明了其氧化过程是多步反应。同时，对原煤样氧化特性测试结果表明，在整个氧化过程中，羟基一直处于降低趋势，而脂肪烃在200℃出现骤降，煤样在200℃左右开始逸出CO、CO₂气体，H₂O从30℃开始产生，120℃开始呈现指数增长。

       通过对比分析类煤模型化合物和原煤的氧化升温过程中的特征参数，结合量子计算，确定了活性官能团的氧化反应历程，进而归纳了其氧化反应机理。研究结果显示，煤在氧化过程中，脂肪烃类活性官能团的C-H键被氧气依次氧化为-OOH和C-O键，且亚甲基（-CH₂-）与氧气的抽氢反应活性要高于甲基（-CH₃）与氧气的抽氢反应，氧化生成的过氧化氢物发生-OH键断裂产生H₂O，C-O键断裂产生CO、CO₂气体，同时伴随着中间体酚类、醛类、酸类物质的产生。羰基类物质会优先发生-OH夺氢生成H₂O的反应，生成的物质再发生C-C键的断裂，生成CO、CO₂气体。而CO₂的直接来源是羧基，CO的直接来源是醛基。亚甲基（-CH₂-）会改变了醛基（-CHO）的活性，使其活性增强。在反应过程中生成的羟基一定程度上会促进反应的进行，加速反应的进程。

       The spontaneous combustion of coal is essentially the result of heat production and accumulation of reactive groups in coal, while the structure of coal is complex and various reactive groups are mixed together. The existing testing methods are difficult to accurately identify the molecules and functional groups involved in the reaction in coal. Thus, it brings great difficulties to reveal the mechanism of coal oxidation reaction. Therefore, based on model compounds, combined with experimental tests and quantum chemical simulation calculations, this paper uses the research idea of discretization of active structures to explore the oxidation reaction mechanism of key active functional groups in coal.

       In this paper, a bituminous coal is selected as the research object, its carbon spectrum and infrared absorption spectrum are measured, and its active functional groups and structural characteristic parameters are determined. The results show that the basic structural units of the coal sample are naphthalene rings, and the average number of carbon atoms in the aromatic layer is 12, and the key active functional groups include hydroxyl (-OH), aromatic ether (Ar-CO), alkyl ether (-C-O-C-), and carbonyl group (-C=O-), methylene (-CH₂-), methyl (-CH₃). Based on this, five simple small molecular structure models (Benzyl phenyl ether, diphenylmethane, naphthalene acetic acid, methoxy naphthalene, 2-phenylacetaldehyde) that can represent the main molecular structure characteristics of the coal sample were constructed using quantum chemistry simulation software. Based on the established small molecule model, five coal-like model compounds were synthesized.

       Through experimental methods such as TG/DSC and TG/MS, the changes in mass, heat, and products of coal-like model compounds during oxidation and heating were studied. The results show that the weight loss of the compound is mainly caused by the release of gas, and when it reaches a certain temperature node, the active functional group will always be in a state of enhanced activity, undergo a violent chemical reaction, and release a large amount of index gas. The compound produced a variety of substances during the oxidation and heating process. The initial appearance temperature and time points of the substances were also different, indicating that the oxidation process was a multi-step reaction. At the same time, the test results of the oxidation characteristics of the raw coal sample showed that during the entire oxidation process, the hydroxyl group had been in a decreasing trend, while aliphatic hydrocarbons dropped sharply at 200℃. The coal sample began to emit CO and CO₂ around 200℃. H₂O started to be produced at 30℃ and began to rise exponentially at 120℃.

       By comparing and analyzing the characteristic parameters in the oxidation heating process of coal-like model compounds and raw coal, combined with quantum calculation, the oxidation reaction process of the active functional groups is determined, and then the oxidation reaction mechanism is summarized. The research results showed that during the oxidation process of coal, the CH bonds of the active functional groups of aliphatic hydrocarbons were sequentially oxidized by oxygen to -OOH bonds and CO bonds, and the hydrogen extraction reaction activity of methylene (-CH₂-) with oxygen was higher than that of methyl (-CH₃). The hydrogen peroxide generated by oxidation would break the -OH bond to produce H₂O, and the break of the CO bond would produce CO and CO₂. At the same time, it would be accompanied by the production of intermediate phenols, aldehydes, and acids. Oxygen of carbonyls would preferentially undergo the reaction of -OH abstraction of hydrogen to generate H₂O, and the resulting material could then break the C-C bond to generate CO and CO₂. The direct source of CO₂ was carboxyl groups, and the direct  source of CO was aldehyde groups. Methylene (-CH₂-) would change the activity of aldehyde group (-CHO) and increased its activity. The hydroxyl generated during the reaction might promote the reaction to a certain extent and accelerated the progress of the reaction.

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