Effect of pore characteristics on coalbed methane adsorption in middle-high rank coals

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• 作者：Xianfeng Liu ; Xueqiu He
• 关键词：Middle ; high rank coal ; Surface chemical characteristics ; Pore structure ; Coalbed methane ; Adsorption capacity
• 刊名：Adsorption
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：23
• 期：1
• 页码：3-12
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Industrial Chemistry/Chemical Engineering; Surfaces and Interfaces, Thin Films; Engineering Thermodynamics, Heat and Mass Transfer;
• 出版者：Springer US
• ISSN：1572-8757
• 卷排序：23

文摘

Gas hazards are still one of the most severe disasters restricting mine safety, and the occurrence of them is heavily dependent on the storage and transportation of methane in coal seams. In order to investigate the influence of pore structure characteristics of middle-high rank coals (V_daf < 25 %) on coalbed methane adsorption, six coal samples of different metamorphism were studied with regard to their surface chemical structure and pore morphological features using Fourier transform infrared (FTIR) spectroscopy, low-pressure nitrogen gas adsorption (LP-N₂GA) and scanning electron microscopy (SEM), and their coalbed methane adsorption capacities were also tested. Based on the Langmuir equation, the Langmuir volume and Langmuir pressure were obtained to characterize the adsorption capacity, and the impact of structural parameters of coal samples on coalbed methane adsorption was analyzed. The results indicate that the pore shape varies a lot between coal samples, suggesting the significant heterogeneity on coal surface. The micropores (<10 nm) in coal samples are well-developed, and the pore size distributions from adsorption analysis are multi-modal. Pore characteristics in coal samples is affected by coalification to a large extent. The adsorption volume of gas mainly concentrates in micropores, and the adsorption capacities of different coal samples display remarkable difference. The Langmuir volume (V_L) is closely related to micropores, but shows little relationship with mesopores, while the Langmuir pressure (P_L) is remarkably affected by both micropores and mesopores. The research results are of great importance for the coalbed methane storage and the accurate prediction of gas emission.