Work

Methane Sorption Behavior in Nanopores of Coal: A Molecular Dynamics Simulation Based on a Reconstructed Macromolecular Model

Year: 2025

Type: article

Abstract: Elucidating the characteristics of methane adsorption in coal is essential for accurately assessing coalbed methane (CBM) potential. Methane adsorption is primarily governed by the compositional complexity of coal and its pore structure. Molecular simulation enables characterization of coal’s molecular composition at the microscopic level and facilitates the construction of nanoscale pore models. In this study, Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the molecular structure of coal. Pore models of various sizes were constructed in Materials Studio (MS) to simulate methane adsorption under different temperatures and pressures. To further clarify the influence of molecular structure, a reconstructed macromolecular model (RMM) was compared with a graphite model, revealing differences in methane adsorption behavior across varying pore sizes, temperatures, and pressures. The results show that absolute methane adsorption increases with pore size, while excess adsorption behavior is strongly associated with the adsorption layer. In the pore size range of 0.4 nm to 1.2 nm, excess adsorption increases due to spatial confinement, but decreases as pore size exceeds 1.2 nm. Structural differences between the RMM and graphite models also resulted in distinct temperature responses, with the graphite model underestimating methane adsorption capacity, highlighting the importance of realistic macromolecular representations in adsorption studies.

Source: Processes

DOI: 10.3390/pr13113478

Authors: Junhan Cheng, Hanlin Liu, Xin Yang, Tao Lei, Qiulei Guo

Institutions: China University of Geosciences, Research Institute of Petroleum Exploration and Development, China National Offshore Oil Corporation (China)

Language: English

Topic: Coal Properties and Utilization

Subfield: Ocean Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Climate action

Open Access status: gold

Estimated APC paid: $2,896