Characteristics of microscopic pore structure and fractal dimension of bituminous coal by cyclic gas adsorption/desorption: An experimental study. (15th November 2018)

• Record Type: Journal Article
• Authors: Wang, Zhenyang; Cheng, Yuanping; Zhang, Kaizhong; Hao, Congmeng; Wang, Liang; Li, Wei; Hu, Biao
• Is Part Of: Fuel. Volume 232(2018)
• Page Start: 495
• Page End: 505
• Publication Date: 2018-11-15
• Subjects: Micropore and mesopore -- Cyclic gas adsorption desorption -- N2 and CO2 adsorption -- Fractal dimensions; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2018.06.004
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Microscopic pore structures of coals were measured by N2 and CO2 adsorption method. Microscopic pore structure was changed with the increasing gas pressures. Two conceptual models are introduced to explain the reasons for the decreased mesopore volume and increased micropore volume. Fractal characteristics are used to analyze pore complexity and the roughness. Abstract: The characteristics of micropore (0.32–2 nm), mesopores (2–50 nm) and fractal dimensions of bituminous coal during the process of cyclic gas adsorption/desorption were revealed by combining N2 (77 K) and CO2 (273 K) adsorption experiments from microscopic aspect. The results indicate that the pore structure characterization in the coal matrix are changed, resulting in decreased mesopore volumes and increased micropore volumes. The mesopore volumes are mainly constituted by the pores of 10–20, and 20–30 nm, and it will increase at first and then decrease with the increasing pressures. The maximum change of micropore volume reaches 65.6%, indicating a great effect on the micropores influenced by pressures. In addition, the main micropore size range, major peak and the model diameter of coals all increase with the increasing pressures, the higher the adsorb pressure is, the higher swelling is. With the help of the conceptual models, we then analyzed the variation reasons, which may be result from transformation of mesopores and the connection of the inaccessible pores. D1 and D2 in #1 and D2 in #2 all increase with the increasing adsorption pressures, enhancing the roughness of surface and complexity of structure, while D1 in #2 shows an opposite property. The study of variations of microscopic pore structure by cyclic adsorption/desorption was aimed at providing new understanding for the exploration of the changes of diffusion and permeability.