为了探究贫氧作用下煤自燃放热关键基团演变特征及其热效应，利用差示扫描量热实验和原位红外实验测试了不同氧气体积分数下煤热反应过程及其微观基团变化规律。结果表明：煤自燃放热过程可分为蒸发吸热、氧化放热、分解蓄热、燃烧放热和燃尽5个阶段，而基团可分为芳香烃化合物、脂肪烃化合物、羟基和碳氧基团4类。随着反应温度的升高，煤中—C=C—逐渐下降，脂肪烃和碳氧基团先增后降，羟基基团则呈两段式下降趋势。随着氧气体积分数的降低，煤反应热流曲线和特征温度向高温区移动，反应强度、放热量和放热特征参数降低。氧气并未改变煤自燃放热进程和基团的变化规律，但会显著影响其关键温度节点。更进一步的，采用灰色关联和量子化学方法确定了关键基团演变特征及其反应热效应。结果表明，任意氧气体积分数下煤自燃放热最关键基团的变化趋势均为—OH-1→—COO—→Ar—CH→Ar—CH，但其关键基团归属则依次为羟基→碳氧基团→脂肪烃化合物→芳香烃化合物。贫氧状态下煤自燃放热过程关键基团及其归属种类并未发生改变。煤自燃过程中H₂O和CO的生成属于自发放热反应，而C₂H₄和C₂H₂生成反应为非自发吸热反应，且C₂H₄和C₂H₂作为自燃标志性气体的灵敏度强于前两者。C₂H₂生成反应是煤放热过程中出现显著吸热峰的关键原因之一，而芳香烃燃烧产生CO和CO₂则是煤燃烧剧烈放热的主要原因之一。

In order to investigate the evolution characteristics of the key groups and their thermal effects under the effect of oxygen-depleted, the thermal reaction process of coal under different oxygen concentrations and the change law of its microscopic groups were studied by using Differential Scanning Calorimetry experiments and in-situ Fourier Transform Infrared Spectroscopy experiments. The results indicate that the coal spontaneous combustion exothermic process can be divided into five stages: evaporation heat absorption, oxidation heat release, decomposition heat storage, combustion heat release, and burnout, and the groups can be categorized into four groups: aromatic hydrocarbon compounds, aliphatic hydrocarbon compounds, hydroxyl groups and carbon-oxygen groups. With the increase of reaction temperature, —C=C— in coal decreased gradually, aliphatic hydrocarbon compounds and carbon-oxygen groups first increased and then decreased, and hydroxyl groups showed a two-stage decreasing trend. With the decrease of oxygen concentration, the coal reaction heat flow curve and characteristic temperature shifted to the high temperature region, and the reaction intensity, heat release and exothermic characteristic parameters decreased. Oxygen did not change the laws of the coal spontaneous combustion exothermic process and variations of groups, but it would significantly affect its key temperature nodes. Further, the grey correlation and quantum chemical methods were used to determine the evolutionary characteristics of key groups and their reactive thermal effects. The results showed that the trend of the most key groups of exothermic process of coal spontaneous combustion at any oxygen concentration was —OH-1→—COO—→Ar—CH→Ar—CH, but the key groups were attributed to hydroxyl group → carbon-oxygen → aliphatic compound → carboxylic compound. The key groups and their attribution had not been changed in the exothermic process of coal spontaneous combustion in the oxygen-depleted state. The production of H₂O and CO during coal spontaneous combustion is a spontaneous exothermic reaction, whereas the reaction of C₂H₄ and C₂H₂ production is a non-spontaneous absorptive reaction, and the sensitivity of C₂H₄ and C₂H₂ as spontaneous combustion indicator gases is stronger than that of the first two. The C₂H₂ generation reaction is one of the key reasons for the emergence of a significant endothermic peak in the coal oxidation exothermic stage, and the combustion of aromatic hydrocarbons to produce CO and CO₂ is one of the main reasons for the intense exothermic process of coal combustion.