构造煤微晶结构的透射电镜分析及其对瓦斯吸附的影响

High-resolution transmission electron microscopy analysis of microcrystalline structure of deformed coal and its effect on gas adsorption

本文以平顶山构造煤为研究对象,基于高分辨透射电镜(HRTEM)图像提取技术定量表征了构造变形影响下微晶结构分布特征:脆性形作用前期煤中芳香簇仅在较小尺寸范围内生长(小于3×3),煤结构演化以应力降解为主;脆性形阶段后期和韧性形阶段,芳香簇已经向较大尺寸方向发展(3×3~8×8),应力缩聚的影响逐渐增强;煤中相对分子质量较低的芳香簇(40~449 Da)受弱变形作用力的影响更为明显,而相对分子质量较高的芳香簇(450~3099 Da)对整个变形过程均有明显响应。结合瓦斯等温吸附实验,阐明了不同变形程度构造煤的分子结构对瓦斯吸附的影响机制:脆性变形阶段,瓦斯吸附能力的提高由煤大分子结构侧链和含氧官能团的脱除、转化等因素导致;韧性变形阶段,芳香结构增加为瓦斯吸附提供了更多吸附位,芳香片层定向排列形成大量层间孔为瓦斯提供了更多吸附空间。研究结果对理解构造煤变形变质特征及其对瓦斯吸附的影响具有重要的科学意义和应用价值。

This article focuses on the study of the microcrystalline structure of coal in the Pingdingshan area using high-resolution transmission electron microscopy(HRTEM).The influence of structural changes resulting from deformation coal is characterized quantitatively.It was found that during the early stage of brittle deformation,the aromatic clusters in the coal only grow within a relatively small size range(less than 3×3),and the evolution of coal structure is mainly characterized by stress degradation.However,during the late stage of brittle deformation and the ductile deformation stage,the aromatic clusters develop towards larger sizes(3×3-8×8),and the influence of stress concentration gradually increases.It was also observed that the coal with dizoer relative molecular weight aromatic clusters(40-449 Da)are more strongly affected by weak deformation,while the higher relative molecular weight aromatic clusters(450-3099 Da)respond more significantly to the entire deformation process.In combination with gas adsorption experiments at constant temperature,the influence mechanism of the molecular structure of coal with different degrees of deformation on gas adsorption was clarified.During the brittle deformation stage,the improvement of gas adsorption capacity was caused by factors such as the removal and conversion of coal macromolecular structure side chains and oxygen-containing functional groups.During the ductile deformation stage,the increase in aromatic structures provides additional adsorption sites,and the oriented arrangement of aromatic sheets forms numerous interlayer pores,thereby providing more adsorption space for gas.The results of this study have important scientific and practical significance for understanding the deformation and metamorphism characteristics of coal and their impact on gas adsorption.