Effect of microwave-assisted cyclic oxidation on the coal internal and surface structure based on NMR and AFM

He Li, Jieyan Cao, Jiexin Lu, Baiquan Lin, Yi Lu, Shiliang Shi, Wei Yang, Yidu Hong, Ting Liu and Meng Liu

Energy, 2024, vol. 288, issue C

Abstract: Exploring new methods for comprehensive mining of coalbed methane (CBM) is a research hotspot. Pore connectivity has a significant impact on the permeability of coal, and as connectivity increases, it has a positive impact on the desorption and seepage of CBM. To quantify and visualize the pore development of coal under three cyclic treatments, T2 and T1-T2 spectra obtained by nuclear magnetic resonance (NMR) and Surface roughness obtained by atomic force microscope (AFM) were selected for characterization. The NMR results indicate that microwave-assisted cyclic oxidation can stimulate the formation of pores and pore throats and effectively dissolve the coal matrix, thereby changing the structure of the coal, manifested by a growth rate of −5.84 % for irreducible porosity and 31.5 % for producible porosity. Cyclic oxidation and microwave have a certain impact on the conversion of micropores to mesopores, but have a relatively less impact on the evolution of new pores. The maximum Rq and Ra obtained by AFM of microwave-assisted cyclic oxidation are 84.7 nm and 70.3 nm, respectively. Moreover, its Rsk and Rku are less than zero and three, respectively. This indicates that microwave-assisted cyclic oxidation has the best effect on changing the internal and surface morphology of coal.

Keywords: Coalbed methane; Microwave-assisted cyclic oxidation; T1-T2 2D spectrum; Pore connectivity; AFM (search for similar items in EconPapers)
Date: 2024
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:288:y:2024:i:c:s0360544223032668

DOI: 10.1016/j.energy.2023.129872

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