煤自燃是影响煤矿安全生产的重大灾害之一，它不仅带来巨大的经济损失，而且带来严重的环境问题。文章采用超声萃取技术，基于量子化学理论，对导致煤自燃的主要活性基团及其对煤氧化特性的影响进行了研究，对揭示煤自燃机理和提高煤自燃防治的针对性具有重要意义。

       选用三种不同变质程度的煤样，采取荧光光谱、核磁共振、原位红外测试技术对所选煤样进行表征，分析了实验煤样的分子结构特征及所携带的关键活性基团，并利用高斯量子化学计算软件对实验所得分子结构模型进行了优化。研究结果表明，变质程度较低的HM主体结构为单芳香环、双芳香环；变质程度中等的YM主体结构为双芳香环、三芳香环结构；变质程度最高的WYM主体结构为三芳香环结构、四芳香环结构。煤样中携带的活性基团主要包括-CH₂CH₃、-COH、-OCH₃、-COOH、-OH等。

      利用量子化学计算软件对溶剂分子结构进行了优化，采取约化密度梯度法研究了煤分子与萃取剂之间的弱相互作用，基于弱相互作用分析优选出对煤样具有良好萃取效果的萃取剂乙二胺和N-甲基吡咯烷酮（NMP）。用两种有机溶剂对三种实验煤样进行超声萃取，并利用GC-MS联用测试系统对萃取产物进行了分析。研究发现，乙二胺分子与煤分子的弱相互作用力主要表现为弱氢键、范德华作用力何位阻作用，可以有效萃取-OH、-COOH等活性基团；NMP分子与煤样分子的弱相互作用力主要表现氢键、弱氢键、范德华作用力和位阻作用，可以有效萃取-OH和含有C=O键的活性基团，而且研究发现NMP对于煤样大分子的萃取作用要优于乙二胺溶剂。

       采用电子自旋共振（ESR）和热重（TG）测试仪器，对3组原煤样和6组萃余煤样的自由基、煤样氧化失重特性和特征温度点的变化进行了分析，得到各活性基团对煤氧化特性的影响。研究发现，-OH是影响煤自燃自由基浓度最重要的基团，分子间缔合-OH对于自由基浓度的影响大于游离-OH。热重测试结果表明，游离-OH对煤样自燃过程中的水分蒸发与脱附阶段影响较大，当游离-OH增多时，临界温度T1下降，煤样水分蒸发与脱附阶段响应变短；分子内缔合-OH对干裂温度T2的影响较大，随着煤样分子内缔合-OH含量的升高，干裂温度T2逐渐降低，吸氧增重阶段变短；脂肪烃与含氧活性基团主要影响煤自燃的活性温度T3，脂肪烃和含氧活性基团的含量增加，煤样吸氧增重阶段变长，且脂肪烃对于该阶段的影响大于含氧活性集团；萃余煤样内Ar-C-O-、-COO-、-COOH等基团含量的增加能够延长萃余煤样受热分解阶段和燃烧阶段，同时导致燃烧阶段的反应更加剧烈。研究结果对阐释活性基团在煤自燃中的作用和揭示煤自燃机理具有重要意义。

     Coal spontaneous combustion is one of the major disasters affecting coal mine safety production. It brings about not only huge economic losses, but also serious environmental problems. In this paper, ultrasonic extraction technology was used to study the effect of main active structure of coal spontaneous combustion on coal oxidation characteristics. This paper is of great significance to reveal the mechanism of coal spontaneous combustion and improve the pertinence of coal spontaneous combustion prevention.

       In this paper, three kinds of coal samples with different metamorphic degrees were selected to characterize the coal samples by Fluorescence Spectrum, Nuclear Magnetic Resonance and Infrared Spectroscopy. Molecular characteristics and active groups of the experimental coal samples were analyzed, and the molecular structure of the experimental coal samples was optimized by Gaussian 16W software. The results showed that the monoaromatic ring and biaromatic ring were the main structures of HM, biaromatic ring and triaryl ring were the main structures of YM, triaryl ring and tetraaromatic ring were the main structures of WYM. The main active groups of coal samples were -CH₂CH₃, -COH, -OCH₃, -COOH, -OH, etc.

        The molecular structure of solvent was optimized by quantum chemistry calculation software, and the weak interaction between coal molecules and extractant was studied by reduced density gradient analysis method. Based on the weak interaction analysis, Ethylenediamine and NMP solvents were selected. Three kinds of experimental coal samples were extracted by two selected organic solvents, and the extracted products were analyzed by GC-MS analysis. The results show that the weak interaction between Ethylenediamine and coal molecules mainly showed weak hydrogen bond, Van Der Waals force and steric hindrance, which could effectively extract -OH and -COOH active groups. The weak interaction between NMP and coal molecules mainly showed hydrogen bond, weak hydrogen bond, Van Der Waals force and potential resistance. NMP could effectively extract -OH and active groups containing C=O bond. The extraction effect of NMP on coal macromolecules was better than that of Ethylenediamine.

        Electron Spin Resonance (ESR) and thermogravimetry (TG) experiments were used to analyze the free radicals, weight loss characteristics and characteristic temperature points of three raw coal samples and six extracted coal samples. The effects of different active groups on the oxidation characteristics of coal were obtained. Free radical experiments show that -OH was the most important active group affecting the concentration of free radicals. The effect of intermolecular association -OH on the concentration of free radical was greater than that of free -OH. The results of thermogravimetric analysis show that free -OH affected the evaporation and desorption stages of coal moisture. With the increase of free -OH, the critical temperature T1 decreased and the period of water evaporation and desorption stage became shorter. The intramolecular association -OH primarily affected the dry cracking temperature T2. As the content of intramolecular association -OH was increased, the catalytic effect of intramolecular association -OH on the reaction would lower the dry cracking temperature T2 and shorten the oxygen-absorption, weight-gain stage. With the increase of the content of aliphatic hydrocarbon and oxygen-containing active group, the period of weight-gain stage became longer. The effect of aliphatic hydrocarbon on this stage was more significant than that of oxygen-containing active group. With the increase of Ar-C-O-, -COO-, -COOH and other groups in the raffinate coal samples, both the thermal decomposition and combustion stages of the raffinate coal samples became longer, and the reaction in the combustion stage was more intense.

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