富油煤是集煤油气属性为一体的煤炭资源，可转化形成清洁燃料和化工原料，对缓解我国缺油现状具有重要意义。富油煤具有一定的煤自燃风险，最大的特征是其富氢结构，相较于含油煤，富油煤低温氧化阶段产生的H₂浓度更高，可以用作指标气体有效预测富油煤自燃状况，因此对富油煤低温氧化产生氢气机理的研究十分必要。本文基于理论分析，实验研究和量子化学模拟，对富油煤低温氧化过程氢气产生的微观机理开展研究。

采用元素及工业分析，¹³C-NMR测试以及FTIR实验，对富油煤芳香碳结构、脂肪碳结构及杂原子赋存形态等结构参数进行表征，利用计算机软件辅助构建富油煤大分子结构模型；通过原位红外光谱实验，研究富油煤低温氧化过程官能团动态变化规律。结果显示：富油煤的含氢结构主要为芳香烃、羟基和羧基；分析得出可能有关H₂产生的微观结构为芳香烃侧链、羧基、醛基和羟基，推断出五个富油煤低温阶段H₂产生反应历程。

基于量子化学模拟，研究富油煤氧化产氢反应历程中目标官能团的结构变化，计算并分析热力学参数。由反应特性及静电式分析得出，氧气首先与醛基反应，亚甲基-次甲基侧链次之，最后是甲基-亚甲基侧链；苯环由于大π键的存在，不易与氧气反应；由热力学分析得出，各反应历程总体吉布斯自由能变均小于0，在常温常压下均可自发进行；结合实验和模拟计算结果得出，富油煤低温氧化H₂产生机理主要为：煤分子中的芳香烃侧链，包括甲基、亚甲基以及次甲基，和氧气反应生成氢气产生的前驱体：羟基、羧基，以及醛基；这些氧化生成和煤中原本存在的结构继续被氧化或相互结合最终成氢气。本文研究成果可以进一步完善煤氧化自燃机理，为开发有效防治富油煤自燃技术提供理论基础，对其安全开采具有重要的科学意义。

Tar-rich coal is a coal resource that integrates coal oil and gas properties, which can be transformed to form clean fuel and chemical raw materials. It is of great significance to alleviate the present situation of oil shortage in our country. Tar-rich coal has a certain risk of coal spontaneous combustion, and the most important feature is its hydrogen-rich structure. Compared with tar-rich coal, the H₂ produced in the low-temperature oxidation stage of tar-rich coal has a higher concentration, which can be used as an indicator gas to effectively predict the situation of tar-rich coal spontaneous combustion. Therefore, it is necessary to study the mechanism of hydrogen produced by low-temperature oxidation of tar-rich coal. Based on theoretical analysis, experimental research and quantum chemical simulation, the microscopic mechanism of hydrogen production during low temperature oxidation of tar-rich coal is studied in this paper.

By using elemental and industrial analysis, ¹³C-NMR and FTIR experiments, the aromatic carbon structure, fatty carbon structure and the occurrence of heteroatoms of tar-rich coal were characterized. The macromolecular structure model of tar-rich coal was constructed with the aid of computer software. The dynamic variation of low temperature oxidation functional groups of tar-rich coal was studied by in-situ infrared spectroscopy. The results show that the hydrogen-containing structure of tar-rich coal is mainly aromatic hydrocarbon, hydroxyl group and carboxyl group. It is concluded that the possible microstructure related to H₂ production is aromatic side chain, carboxyl group, aldehyde group and hydroxyl group, and the reaction history of H₂ production in five tar-rich coals at low temperature stage is deduced.

Based on quantum chemical simulation, the structural changes of target functional groups in the process of hydrogen-producing oxidation of tar-rich coal were studied, and the thermodynamic parameters were calculated and analyzed. According to the reaction characteristics and electrostatic analysis, oxygen reacts first with aldehyde group, followed by methylene - methyne side chain, and finally with methyl - methylene side chain. Benzene ring is not easy to react with oxygen due to the existence of large π bond. According to thermodynamic analysis, the Gibbs free energy variation of each reaction process is less than 0, and can be spontaneous under normal temperature and pressure. Combined with the experimental and simulation results, it is concluded that the low temperature H₂ oxidation mechanism of tar-rich coal is mainly as follows: the aromatic hydrocarbon side chains in coal molecules, including methyl, methylene and methyne, react with oxygen to produce hydrogen precursor: hydroxyl, carboxyl and aldehyde groups; These oxidizes form with the existing structures in the coal that continue to oxidize or combine with each other to form hydrogen gas. The research results of this paper can further improve the mechanism of coal oxidation spontaneous combustion, provide a theoretical basis for the development of effective prevention and control of tar-rich coal spontaneous combustion technology, and have important scientific significance for its safe mining.

[1]薛黎明,王豪杰, 朱兵兵, 等. 煤炭资源可持续力评价与系统协调发展分析[J]. 经济地理, 2020, 40(1): 114-124．

[2]2020中国统计年鉴. [J]. 统计理论与实践, 2021(01): 2.

[3]赵开功, 李彦平. 我国煤炭资源安全现状分析及发展研究[J]. 煤炭工程, 2018, 50(10): 185-189.

[4]马丽, 王双明, 段中会, 等. 陕西省富油煤资源潜力及开发建议[J]. 煤田地质与勘探, 2022, 50(2): 1-8.

[5]许婷,李宁,姚征,王强,谢青,高骏.陕北榆神矿区富油煤分布规律及形成控制因素[J].煤炭科学技术,2022,50(03):161-168.

[6]王双明, 师庆民, 王生全, 申艳军, 孙强, 蔡玥. 富油煤的油气资源属性与绿色低碳开发[J]. 煤炭学报, 2021,46(05):1365-1377.

[7]Taraba B, Michalec Z. Effect of longwall face advance rate on spontaneous heating process in the gob area—CFD modelling[J]. Fuel, 2011, 90(8): 2790-2797.

[8]Shao Z, Wang D, Wang Y, et al. Controlling coal fires using the three-phase foam and water mist techniques in the Anjialing Open Pit Mine, China[J]. Natural Hazards, 2015, 75(2): 1833-1852.

[9]Wang K, Deng J, Zhang Y, et al. Kinetics and mechanisms of coal oxidation mass gain phenomenon by TG-FTIR and in situ IR analysis[J]. Journal of Thermal Analysis and Calorimetry, 2018, 132(1): 591-598.

[10]Wang S, Luo K, Wang X, et al. Estimate of sulfur, arsenic, mercury, fluorine emissions due to spontaneous combustion of coal gangue: An important part of Chinese emission inventories[J]. Environmental Pollution, 2016, 209: 107-113.

[11]Zhou K, Xu M, Yu D, et al. Formation and control of fine potassium-enriched particulates during coal combustion[J]. Energy & fuels, 2010, 24(12): 6266-6274.

[12]Xu Y, Liu X, Wang H, et al. Investigation of simultaneously reducing the emission of ultrafine particulate matter and heavy metals by adding modified attapulgite during coal combustion[J]. Energy & Fuels, 2018, 33(2): 1518-1526.

[13]费金彪. 煤自然阶段判定理论与分级预警方法研究[D]. 陕西: 西安科技大学, 2019.

[14]张玉龙. 基于宏观表现与微观特性的煤低温氧化机理及其应用研究[D]. 太原: 太原理工大学, 2014.

[15]张嬿妮. 煤氧化自燃微观特征及其宏观表征研究[D]. 西安: 西安科技大学, 2012.

[16]杨甫,段中会,马丽,付德亮,田涛,贺丹,岳明娟.陕西省富油煤分布及受控地质因素[J].煤炭科学技术,2023,51(03):171-181.

[17]李华兵,姚征,李宁,高骏,谢青,王强.神府矿区5-2煤层富油煤赋存特征及资源潜力评价[J].煤田地质与勘探,2021,49(03):26-32+41.

[18]徐精彩. 煤自燃危险区域判定理论[M]. 北京: 煤炭工业出版社, 2001.

[19]文虎. 煤自燃过程的实验及数值模拟研究[D]. 西安科技大学, 2003.

[20]Xu Q, Yang S, Cai J, et al. Risk forecasting for spontaneous combustion of coals at different ranks due to free radicals and functional groups reaction[J]. Process Safety and Environmental Protection, 2018, 118: 195-202.

[21]张玉涛, 李亚清, 邓军, 张辛亥. 煤炭自燃灾变过程突变特性研究[J]. 中国安全科学学报, 2015, 25(01): 78-84.

[22]Arisoy A, Beamish B. Reaction kinetics of coal oxidation at low temperatures[J]. Fuel, 2015, 159: 412-417.

[23]戚绪尧. 煤中活性基团的氧化及自反应过程[D]. 徐州: 中国矿业大学, 2011.

[24]Ming-gao Y, Yan-min Z, Chang L. Thermal analysis of kinetics of coal oxidation[J]. Procedia Earth and Planetary Science, 2009, 1(1): 341-346.

[25]Wang K, Han T, Deng J, et al. Comparison of combustion characteristics and kinetics of Jurassic and Carboniferous-Permian coals in China[J]. Energy, 2022, 254: 124315.

[26]Wang K, Hu L, Deng J, et al. Multiscale thermal behavioral characterization of spontaneous combustion of pre-oxidized coal with different air exposure time[J]. Energy, 2023, 262: 125397.

[27]何启林, 任克斌, 王德明. 用红外光谱技术研究煤的低温氧化规律[J]. 煤炭工程,2003, (11): 45-48．

[28]余明高, 贾海林, 徐俊. 乌达烟煤的微观结构与自燃的关联性分析[J]. 辽宁工程技术大学学报, 2006,25(6): 819-822．

[29]张辛亥, 罗振敏, 张海珩. 煤自燃性的红外光谱研究[J]. 西安科技大学学报, 2007, 27(2): 171-186．

[30]Wang K, Deng J, Zhang Y, et al. Kinetics and mechanisms of coal oxidation mass gain phenomenon by TG-FTIR and in situ IR analysis[J]. Journal of Thermal Analysis and Calorimetry, 2018, 132: 591-598.

[31]Fan H, Wang K, Zhai X, et al. Combustion kinetics and mechanism of pre-oxidized coal with different oxygen concentrations[J]. ACS omega, 2021, 6(29): 19170-19182.

[32]杜淑凤. 用X-射线能谱(XPS)和二次离子质谱(SIMS)分析法研究烟煤镜质组低温氧化过程初探[J]. 煤质技术, 2001,(S1): 38-43．

[33]Li J, Lu W, Cao Y, et al. Method of pre-oxidation treatment for spontaneous combustion inhibition and its application[J]. Process Safety and Environmental Protection, 2019, 131: 169-177.

[34]Wang K, Hu L, Sun W, et al. Influences of the pre-oxidation time on coal secondary spontaneous combustion behaviors by temperature-programmed technique[J]. International Journal of Coal Preparation and Utilization, 2022: 1-13.

[35]刘利, 崔文权, 陈鹏, 等. 利用XPS研究低温干燥脱水过程中煤的氧化规律[J].煤炭技术,2010,29(5):189-191.

[36]Chen X, Ma T, Zhai X, et al. Thermogravimetric and infrared spectroscopic study of bituminous coal spontaneous combustion to analyze combustion reaction kinetics[J]. Thermochimica Acta, 2019, 676: 84-93.

[37]Liang Y, Tian F, Guo B, et al. Experimental investigation on microstructure evolution and spontaneous combustion properties of aerobic heated coal[J]. Fuel, 2021, 306: 121766.

[38]Zhao J, Wang W, Fu P, et al. Evaluation of the spontaneous combustion of soaked coal based on a temperature-programmed test system and in-situ FTIR[J]. Fuel, 2021, 294: 120583.

[39]辛海会, 王德明, 戚绪尧,等. 褐煤表面官能团的分布特征及量子化学分析[J]. 北京科技大学工程,2013,35(2):135-139.

[40]Shi T, Wang X, Deng J, et al. The mechanism at the initial stage of the room-temperature oxidation of coal[J]. Combustion and Flame, 2005, 140(4): 332-345.

[41]王德明, 辛海会, 戚绪尧, 窦国兰, 仲晓星. 煤自燃中的各种基元反应及相互关系: 煤氧化动力学理论及应用[J]. 煤炭学报, 2014, 39(08): 1667-1674.

[42]孙庆雷, 李文, 陈皓侃, 等. 煤显微组分分子结构模型的量子化学研究[J]. 燃料化学学报,2004,32(3):282-286．

[43]Sun Q L, Wen L I, Dong tao L I, et al. Relationship between structure characteristics and thermal conversion property of Shenmu maceral concentrates[J]. Journal of Fuel Chemistry & Technology, 2003, 31(2):97-102.

[44]Xu T. Heat effect of the oxygen-containing functional groups in coal during spontaneous combustion processes[J]. Advanced Powder Technology, 2017, 28(8): 1841-1848.

[45]Zhang Y, Shu P, Deng J, et al. Analysis of oxidation pathways for characteristic groups in coal spontaneous combustion[J]. Energy, 2022, 254: 124211.

[46]Zhu H, Huo Y, Wang W, et al. Quantum chemical calculation of reaction characteristics of hydroxyl at different positions during coal spontaneous combustion[J]. Process Safety and Environmental Protection, 2021, 148: 624-635.

[47]邓军,李亚清,张玉涛等.羟基(-OH)对煤自燃侧链活性基团氧化反应特性的影响[J].煤炭学报,2020,45(01):232-240.

[48]Qi X, Xue H, Xin H, et al. Quantum chemistry calculation of reaction pathways of carboxyl groups during coal self-heating[J]. Canadian Journal of Chemistry, 2017, 95(8): 824-829.

[49]Qi X, Wang D, Xue H, et al. Oxidation and self-reaction of carboxyl groups during coal spontaneous combustion[J]. Spectroscopy Letters, 2015, 48(3): 173-178.

[50]Fan L, Meng X, Zhao J, et al. Reaction site evolution during low-temperature oxidation of low-rank coal[J]. Fuel, 2022, 327: 125195.

[51]Zhang X, Lu B, Zhang J, et al. Experimental and simulation study on hydroxyl group promoting low-temperature oxidation of active groups in coal[J]. Fuel, 2023, 340: 127501.

[52]王省身, 张国枢. 矿井火灾防治[M]. 徐州: 中国矿业大学出版社, 1990.

[53]谢克昌. 煤的结构与反应性[M]. 北京: 科学出版社, 2002.

[54]梁汉东. 煤岩自然释放氢气与瓦斯突出关系初探[J]. 煤炭学报, 2001, 6(26): 637-642.

[55]杨忠红, 马婧. 地质勘探过程中煤层气联测氢气方法[J]. 地质学报, 2009, 2(29): 244-246.

[56]戴广龙, 张国枢, 邵辉. 新集煤矿采空区氢气与煤炭自燃氧化关系的研究[J]. 煤炭工程师, 1998, 2: 12-15.

[57]Krzysztof Stanczyk, Krzysztof Kapusta, Marian Wiatowski et al. Experimental simulation of hard coal underground gasification for hydrogen production. Fuel 2012, 91, 40-50.

[58]He, Shao; Fubao, Zhou; Kaiyan, Chen; Jianwei, Cheng. Study on the hydrogen generation rules of coal oxidation at low temperature[J]. Technological Education Institute of Kavala. 2014, 90-95.

[59]Wang Y, Wu J, Xue S, et al. Hydrogen production by low-temperature oxidation of coal: Exploration of the relationship between aliphatic CH conversion and molecular hydrogen release[J]. International Journal of Hydrogen Energy, 2017, 42(39): 25063-25073.

[60]Grossman, Samuel L., Davidi, Shoshana; Cohen. Molecular hydrogen evolution as a consequence of atmospheric oxidation of coal: 3. Thermogravimetric flow reactor studies[J]. Fuel, 1994, 762-767.

[61]Nehemia V, Davidi S, Cohen H. Emission of hydrogen gas from weathered steam coal piles via formaldehyde as a precursor: I. Oxidative decomposition of formaldehyde catalyzed by coal–batch reactor studies[J]. Fuel, 1999, 78(7): 775-780.

[62]Wang Y, Wu J, Xue S, et al. Experimental study on the molecular hydrogen release mechanism during low-temperature oxidation of coal[J]. Energy & Fuels, 2017, 31(5): 5498-5506.

[63]任浩婕. 煤氧化热解过程中氢气生成的规律的研究[D]. 太原, 太原理工大学, 2012.

[64]姚彦娜. 煤自燃过程H2生成规律及与其它指标气体关联性研究[D]. 太原, 太原理工大学, 2015.

[65]周强. 煤层瓦斯中氢气与氦气的气象色谱分析方法与应用研究[D]. 北京,中国原子能科学, 2004.

[66]王涌宇. 煤氧化过程中氢气生成特性和释放机理的实验研究[D].太原理工大学,2017.

[67]Singh A K, Singh R V K, Singh M P, et al. Mine fire gas indices and their application to Indian underground coal mine fires[J]. International Journal of coal geology, 2007, 69(3): 192-204.

[68]Grossman S L, Davidi S, Cohen H. Molecular hydrogen evolution as a consequence of atmospheric oxidation of coal: 1. Batch reactor simulations[J]. Fuel, 1993, 72(2): 193-197.

[69]Fubao Z, Jinhai L I, Yusheng L I U, et al. Rules of variation in hydrogen during reignition of underground fire zones of spontaneous coal combustion[J]. Mining Science and Technology, 2010, 20(4): 499-503.

[70]Xiaoqiang Li, Bernhard M. Krooss, Philipp Weniger et al. Liberation of molecular hydrogen (H2) and methane (CH4) during non-isothermal pyrolysis of shales and coals: Systematics and quantification. International Journal of Coal Geology 2015, 137,152-164.

[71]Casal M D, Gonzalez A I, Canga C S, et al. Modifications of coking coal and metallurgical coke properties induced by coal weathering[J]. Fuel processing technology, 2003, 84(1-3): 47-62.

[72]Cohen, H. Green U. Oxidative decomposition of formaldehyde catalyzed by a bituminous coal[J]. Energy & Fuel 2009, 23: 3078-3082.

[73]Lopez D, Sanada Y, Mondragon F. Effect of low-temperature oxidation of coal on hydrogen-transfer capability[J]. Fuel, 1998, 77(14): 1623-1628.

[74]Yoshiie R, Onda M, Ueki Y, et al. Oxygen chemisorption and low-temperature oxidation behaviors of sub-bituminous coal[J]. Journal of Thermal Science and Technology, 2019, 14(1): JTST0005-JTST0005.

[75]Yin Z, Xu H, Chen Y, et al. Experimental simulate on hydrogen production of different coals in underground coal gasification[J]. International Journal of Hydrogen Energy, 2023, 48(19): 6975-6985.

[76]戴广龙. 煤低温氧化及自燃特性的综合实验研究[M]. 徐州:中国矿业大学出版社. 2010(7).

[77]张志军, 王露, 李浩. 煤分子结构模型构建及优化研究[J]. 煤炭科学技术，2021,49( 2): 245-253.

[78]刘春辉. 侏罗纪煤热反应模型构建及氧化历程研究[D].西安科技大学,2021.

[79]严煌. 无烟煤分子结构特征及热解过程中官能团迁移特性研究[D].中国矿业大学,2019.

[80]Zhu H, Huo Y, He X, et al. Molecular model construction of Danhou lignite and study on adsorption of CH4 by oxygen functional groups[J]. Environmental Science and Pollution Research, 2021, 28(20): 25368-25381.

[81]Li B, Liu S, Guo J, et al. Interaction between low rank coal and kaolinite particles: A DFT simulation[J]. Applied Surface Science, 2018, 456: 215-220.

[82]Grimme S. Density functional theory with London dispersion corrections[J]. Wiley Interdisciplinary Reviews: Computational Molecular Science, 2011, 1(2): 211-228.

Grimme S, Antony J, Ehrlich S, et al. A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu [J]. The Journal of chemical physics, 2010, 132(15): 154104.