School of Geoscience and Surveying Engineering, China University of Mining and Technology-Beijing

煤炭既是重要的能源资源,也是潜在的材料原料。作为能源时,煤的物理结构在其综合利用及转化中有不可忽视的作用,如煤中孔隙结构对煤层气的储存、吸附、运移、解吸等有关键性作用。作为材料原料时,能为高精尖产业提供优质原料来源,如煤基石墨、煤基石墨烯等。显微组分是煤的主要成分,对煤的属性及其应用贡献巨大。以榆横矿区小纪汗煤矿 2 号煤层样品(XJH)为研究对象,对煤中显微组分开展原子力显微镜(AFM)观测,分析镜质组、半丝质体和丝质体的微观形貌和孔隙结构特征,为该区煤的清洁高效利用夯实基础。结果显示,XJH 煤显微组分的微观形貌以粒状结构为主,表面颗粒呈不同规则程度圆形或椭圆形随机分布;镜质组表面颗粒的功率谱密度分形维数 Ds最大,颗粒空间充填能力和高低起伏程度大,随机性强,微观结构较复杂。半丝质体次之。丝质体Ds 最小,颗粒分布较疏散,起伏程度较缓,微观结构较镜质组和半丝质体简单。孔隙结构方面,镜质组孔隙平均孔径和面积最小,但孔隙数量最多,且贡献主要来自孔径<2 nm 的微孔,镜质组孔隙结构更利于煤层气的吸附和储存;惰质组平均孔径和面积大于镜质组,但孔隙数量更少,这是惰质组中孔径 2~50 nm 的介孔数量较多所致,惰质组的孔隙结构能为煤层气的扩散提供有利通道。惰质组中半丝质体和丝质体的孔隙结构都主要由介孔贡献,但半丝质体孔隙分形维数 D 较大,即半丝质体孔隙不规则程度较丝质体大。

Coal is not only important energy resource, but also potential source of materials. As energy resource, coal has these physicalproperties which are important for comprehensive applications and transformations. For example, the pore structure of coal is crucial forthe reservoir, adsorption, and migration and desorption of coal bed methane. As feedstock of materials, coal can provide good raw material for special technological fields, such as graphite and graphene from coal. Macerals are the main components of coal, which are significant for properties and applications of coal. Taking coal sample (XJH) from No. 2 coal seam of Xiaojihan coal mine, Yuheng mining area asthe object of this study, macerals were observed by atomic force microscope (AFM). Micro morphology and pore structure of vitrinite,semifusinite and fusinite are analyzed to provide fundamentals for clean and comprehensive application of coal in this area. Results showthat the micro morphology is featured by granular structure with randomly distributed granules. Vitrinite has the largest Ds value, indicating a complex micro morphological structure. Granules accumulate densely and fluctuate in large extent. Semifusinite has a medium Dsvalue. Fusinite has the smallest Ds value, and granules accumulate dispersedly and fluctuate in small extent. As for pore structure, vitrinitehas the lowest value of mean pore size and volume, but has the largest pore number. It results from the micro pores sized below 2 nm. Thepore structure of vitrinite is beneficial to reservoir and adsorption of coal bed methane. Inertinite has larger pore size and volume than vitrinite, but the pore number is less. This is mainly contributed by pores sized in 2~50 nm. The pore structure of inertinite can provide beneficial space for the diffusion of coal bed methane. Inertinite is dominated in pores sized in 2~50 nm, but fractal dimension of pores (D) ofsemifusinite is larger than fusinite, indicating pores in semifusinite has larger irregular degree than fusinite.

国家自然科学基金面上资助项目(42072196,42030807)

张小梅, 王绍清, 陈昊, 等. 基于原子力显微镜观测的煤中显微组分微观形貌与孔隙结构[J]. 煤炭科学技术, 2023, 51(4):127-132.

ZHANG Xiaomei, WANG Shaoqing, CHEN Hao. Micro morphology and pore structure of macerals in coal observed by atomic forcemicroscopy (AFM)[J]. Coal Science and Technology, 2023, 51(4): 127-132.