为研究不同煤阶煤制生物甲烷产量出现差异的可能性原因，选择长焰煤、焦煤和瘦煤三种不同煤阶煤样，通过对不同煤阶生物甲烷含量测定、GC-MS(气相色谱-质谱联用仪）测试和扫描电镜检测，分析煤制生物甲烷的成气特征、有机物组成与煤表面结构变化规律以及菌群附着特征。研究发现，煤阶越高，生物产气总量越低，并且低煤阶煤的生物甲烷产量明显高于高煤阶煤。通过GC-MS测试，3个煤阶煤生物产气过程第10天有挥发性脂肪酸（VFA）和甲基化合物等物质生成，长焰煤试验组与焦煤试验组在第15天未检测到VFA等小分子物质存在，并且伴随有新的大分子物质生成，瘦煤试验组并未在第15天检测到VFA，可能归因于瘦煤试验组发酵后期产甲烷菌活性的降低。同时，高的脂肪酸含量是抑制甲烷生成的原因之一，芳香烃较脂肪烃更适合被微生物降解，所以其在液相产物中的占比也是影响最终甲烷生成量的主要因素。扫描电镜检测结果显示，3种煤样表面细胞形态有明显差异，且在产气高峰期3种煤样表面细胞密度均有所增加，长焰煤表面凹凸不平，粗糙度逐渐增加，焦煤与瘦煤表面无明显变化。以上研究结果表明：低阶煤更适合作为碳源供产甲烷菌利用，液相产物中VFA、脂肪酸和芳香烃含量可间接反应煤制生物甲烷反应的剧烈程度，也可以间接表征煤样表面菌群的吸附特征，并且煤样表面菌群细胞密度与生物甲烷产气量之间成正比关系。这些结果为煤的液化以及清洁利用提供借鉴。

In order to investigate the difference of biogas production from different rank coal samples, long flame coal, coking coal and lean coal were chosen to analyze the biogas production characteristics, organic matter composition, coal surface structure and characteristics of microbial adsorption by the determination of the biomethane production and GC-MS(Gas chromatograph- mass spectrometer), scanning electron microscope tests. The results showed that the higher the coal rank is, the lower the cumulative biogas production is, and the biogas production of low rank coals was significantly higher than that of high rank coals. For the results of GC-MS tests, VFA(Volatile Fatty Acid) and methyl compounds were produced in the 10th day of biogas generation process, while the VFA and other small molecular substances were not detected in the 15th day of the long flame coal experimental group and coking coal experimental group, new macromolecular substances were generated. However, VFA was still detected in the lean coal experimental group, this may be attributed to the decrease of methanogens activity in the late stage of fermentation. At the same time, the content of high fatty acid is one of the reasons for inhibiting methane generation. Aromatic hydrocarbons are more suitable for microbial degradation than aliphatic hydrocarbons, so its proportion in liquid products is also the main factor for affecting the final methane production. At the same time, it is different from the cell morphology of coal surface, and the cell density increased in the peak period of biogas production from three coal samples. The surface of the long flame coal was uneven, and the surface roughness increased gradually. There is no obvious change in the surface structure of coking coal and lean coal. The above results showed that low rank coal was more suitable as carbon source for methanogens. The VFA, fatty acid and aromatic hydrocarbons contents in the fermentation solution can indirectly reflect the intensity for the conversion of coal to biogas, it can also indirectly characterize the adsorption characteristics of bacteria on coal surface. There is a positive relationship between the cell density of bacterial community on the surface of coal samples and biogas production, which provides reference for the coal liquefaction and clean utilization of coal.