为探究厌氧微生物降解作用下镜煤与暗煤化学结构差异特征及其演化规律，以黄陵矿区侏罗系延安组2号煤层（原煤、镜煤与暗煤）为研究对象，进行厌氧微生物降解不同类型煤生烃模拟试验，利用傅里叶红外光谱和X射线衍射技术分析不同降解阶段下（Ⅰ、Ⅱ、Ⅲ阶段）煤的官能团结构和微晶结构演化特征。结果表明，镜煤与暗煤累计甲烷产量分别为343.58和281.13 μmol/g，镜煤产气高峰期比暗煤产气高峰期出现时间早14 d。受宏观煤岩类型影响，镜煤高取代芳烃占比明显大于暗煤，且脂肪结构侧支链更丰富，暗煤则富集含氧官能团和芳香结构，其微晶结构更稳定。微生物降解煤的主要官能团是不稳定的脂肪结构侧支链，镜煤和暗煤脂肪结构CH₂/CH₃比值分别从2.20和1.77增加至2.36和2.17，芳香碳含量的变化不超过0.05，其他官能团结构演化无统一规律。微晶结构参数中镜煤和暗煤堆砌度和堆砌层数降低，L_c分别从1.28 nm和1.38 nm降低至1.22 nm和1.27 nm，N_ave分别从3.51和3.82降低至3.34和3.50，碳原子网面间距增大，即芳香结构弱桥键断裂，芳香核边缘不规则小分子量芳香层片脱落。变异系数散点图显示镜煤与暗煤的芳烃取代基区间变异程度最大，镜煤微晶结构变异程度明显高于暗煤。微生物降解作用下镜煤前期主要脱落芳香层片之间填充的有机物，碳原子面网间距降低，同时会破坏芳香结构，引起脂肪结构丰度增加，暗煤前期主要脱落芳香核边缘脂肪结构和含氧官能团，在微生物降解镜煤和暗煤的整个过程中脂肪结构始终被破坏，芳香结构桥键逐渐断裂，引起芳香核边缘结构解体。

To explore variations in chemical composition and evolutionary trends between vitrain and durain during anaerobic microbial degradation, we performed simulation experiments on hydrocarbon generation through anaerobic microbial degradation using samples from No.2 coal seam (raw coal, vitrain, and durain) sourced from the Jurassic Yan'an Formation in the Huangling Mining area. Fourier transform infrared spectroscopy and X-ray diffraction techniques were utilized for analyzing changes in functional group structures as well as microcrystalline structural evolution at different stages (I, II, III) of degraded coals. The results indicate that the cumulative methane production from mirror coal and dark coal was 343.58 μmol/g and 281.13 μmol/g, respectively. The peak gas production time for vitrain occurs 14 days earlier compared to that of durain. Notably, the peak gas production time for vitrain occurred two week earlier compared to durain. Furthermore, vitrain exhibits a substantially higher proportion of highly substituted aromatic hydrocarbons in comparison to durain. Additionally, the aliphatic structure exhibits a greater abundance of side chains in vitrain. On the other hand, durain is characterized by an enrichment of oxygen-containing functional groups and aromatic structures, along with a more stable microcrystalline structure. Microbial degradation primarily affected the unstable side chains of the aliphatic structure. Under microbial degradation, the CH₂/CH₃ ratio of the aliphatic structure in vitrain and durain increased from 2.20 to 2.36 and from 1.77 to 2.17, respectively. The aromatic carbon content remained virtually unchanged, with variations not exceeding 0.05. Additionally, other functional groups did not exhibit a consistent trend. Among the microcrystalline structural parameters, both the stacking degree and the number of stacking layers for vitrain and durain exhibited a decrease. Specifically, the L_c values decreased from 1.28 nm and 1.38 nm to 1.22 nm and 1.27 nm, respectively, while the average number of stacking layers (N_ave) decreased from 3.51 and 3.82 to 3.34 and 3.50, respectively. Additionally, the interlayer spacing between carbon atoms increased, indicating a weakening of bridge bonds within the aromatic structures. This phenomenon resulted in the shedding of irregular low molecular weight aromatic lamellae at the edges of the aromatic nuclei. Changes in microcrystal structure were characterized by weakened bridge bond fractures, irregular edges of basic structural unit, shedding of small molecular weight aromatic layer sheets. The coefficient of variation indicates that the degree of variation in aromatic substituents is highest in vitrain and durain, while the degree of variation in microcrystalline structure is significantly greater in vitrain compared to durain. The structural evolution of vitrain and durain differs during microbial degradation. In the initial stage of vitrain, shedding of organic matter between aromatic layers results in a reduction in carbon atom spacing, damage to the aromatic structure, and an increase in aliphatic structures. In the early stage of durain, shedding occurs for both aliphatic structures and oxygen-containing functional groups at the edge of the basic structural unit. Throughout the entire process of microbial degradation for both vitrain and durain, aliphatic structures are destroyed and gradual breakdown of aromatic bridge bonds leads to disintegration of the edge structure of the basic structural unit.