Wu Dun, Wei Jianghao, Zhao Shoule, Sun Lin, Li Yunfeng
Key Laboratory of Intelligent Underground Detection Technology, College of Civil Engineering, Anhui Jianzhu University, Hefei, China.
School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China.
J Microsc. 2025 Aug 26. doi: 10.1111/jmi.70028.
The pore structure characteristics of coal are crucial for coalbed methane adsorption and migration, carbon storage, and safety in deep coal mining. Although traditional methods can detect pore volume and distribution, they are limited in analysing pore morphology and surface properties. This study employs multiscale techniques including AFM (Atomic force microscopy), SEM (Scanning electron microscopy), and LP-NGA (Low-Pressure nitrogen gas adsorption) to systematically analyse the impact of coal rank changes on pore structure and its evolutionary process, covering coals from medium-volatile to low-volatile bituminous and anthracite coals. AFM reveals the three-dimensional morphology and quantitative parameters of nanopores, SEM observes meso- and micropore structures, and LP-NGA verifies pore size distribution. As coal rank increases, surface roughness decreases significantly, the number of pores increases, the average pore diameter decreases, pore morphology transforms from irregular to circular, and porosity increases. Specifically, as the rank of coal increases, the number of nanoring structures rises, while their diameters decrease. Changes in coal rank profoundly affect the nanoring structure, consistent with the evolutionary trend of surface morphology. The combination of AFM and LP-NGA reveals the role of micropores in gas adsorption. This research not only provides a new perspective for understanding the influence of coal rank changes on pore structure characteristics but also offers a theoretical foundation for coalbed methane development, geological sequestration of carbon dioxide, design of coal-based functional materials, and coal mine safety prevention and control.
煤的孔隙结构特征对于煤层气的吸附与运移、碳封存以及深部煤炭开采的安全性至关重要。尽管传统方法能够检测孔隙体积和分布，但在分析孔隙形态和表面性质方面存在局限性。本研究采用包括原子力显微镜（AFM）、扫描电子显微镜（SEM）和低压氮气吸附（LP-NGA）在内的多尺度技术，系统地分析煤阶变化对孔隙结构及其演化过程的影响，研究范围涵盖中挥发分至低挥发分烟煤以及无烟煤。AFM揭示了纳米孔的三维形态和定量参数，SEM观察了中孔和微孔结构，LP-NGA验证了孔径分布。随着煤阶的升高，表面粗糙度显著降低，孔隙数量增加，平均孔径减小，孔隙形态从不规则变为圆形，孔隙率增加。具体而言，随着煤阶的升高，纳米环结构的数量增加，而其直径减小。煤阶变化深刻影响纳米环结构，这与表面形态的演化趋势一致。AFM和LP-NGA的结合揭示了微孔在气体吸附中的作用。本研究不仅为理解煤阶变化对孔隙结构特征的影响提供了新视角，也为煤层气开发、二氧化碳地质封存、煤基功能材料设计以及煤矿安全防治提供了理论基础。
