Title: Effect of moisture content on methane diffusion in kaolinite by molecular dynamics simulations

Authors: Bin Zhang; Guanxian Kang; Xiaoyu Zhang; Tianhe Kang

Addresses: Key Laboratory of In-situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, No. 18 New Mining Road, Taiyuan, 030024, China ' College of Safety and Emergency Management Engineering, Taiyuan University of Technology, No. 18 New Mining Road, Taiyuan, 030024, China ' Key Laboratory of In-situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, No. 18 New Mining Road, Taiyuan, 030024, China ' Key Laboratory of In-situ Property-Improving Mining of Ministry of Education, Taiyuan University of Technology, No. 18 New Mining Road, Taiyuan, 030024, China

Abstract: The diffusion behaviours of methane in kaolinite with water contents ranging from 0-5 wt% are analysed by molecular dynamics (MD) simulations. The results indicate that methane molecules can jump between adjacent holes in the kaolinite matrix. The methane diffusion coefficient is very low (3.28 × 10⁻⁹ m²/s) and linearly increases with the increasing moisture content. As the moisture content decreases, the value of the first RDF peak between methane and oxygen is larger, indicating that with a lower moisture content, the interaction energy between methane and oxygen in kaolinite is stronger. The interaction between methane and water linearly increases with the moisture content; by contrast, the interaction energy between kaolinite and water and between kaolinite and methane linearly decreases with the increasing moisture content. The diffusion of methane molecules adsorbed on the surfaces can also be accelerated by the fast diffusion of water molecules in the middle interlayer nanopores of the kaolinite. [Received: May 12, 2019; Accepted: September 17, 2019]

Keywords: molecular dynamics; kaolinite; moisture content; diffusion.

DOI: 10.1504/IJOGCT.2021.111880

International Journal of Oil, Gas and Coal Technology, 2021 Vol.26 No.1, pp.84 - 95

Received: 12 May 2019
Accepted: 17 Sep 2019
Published online: 18 Dec 2020 *

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