Adsorption and diffusion characteristics of CH4, CO2, and N2 in micropores and mesopores of bituminous coal: Molecular dynamics

[Display omitted] •The micropore and mesopore models of bituminous coal were established.•Simulation of unary CH4, CO2 and N2 adsorbed into micro- and meso-pores of coal by Monte Carlo simulation.•Pore size had a great influence on gas adsorption and diffusion.•In micro- and meso-pores, the effectiv...

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Bibliographic Details
Published in:Fuel (Guildford) 2021-05, Vol.292, p.120268, Article 120268
Main Authors: Long, Hang, Lin, Hai-fei, Yan, Min, Bai, Yang, Tong, Xiao, Kong, Xiang-guo, Li, Shu-gang
Format: Article
Language:English
Subjects:
Adsorption
Atomic radius
Bituminous coal
Carbon dioxide
Coal
Diffusion
Distribution functions
Gaseous diffusion
Gases
Isometric
Isosteric heat of loading
Methane
Micropores and mesopores of bituminous coal
Molecular dynamics
Molecular modelling
Pore size
Pores
Radial distribution
Radial distribution function
Self-diffusion coefficient
Tight adsorption amount
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Summary:[Display omitted] •The micropore and mesopore models of bituminous coal were established.•Simulation of unary CH4, CO2 and N2 adsorbed into micro- and meso-pores of coal by Monte Carlo simulation.•Pore size had a great influence on gas adsorption and diffusion.•In micro- and meso-pores, the effective distance and radius of action between coal molecules and gas molecules were different. The characteristics of gas loading, diffusion and adsorption in pore models of coal molecules within variety pore sizes were different. The Grand canonical Monte Carlo and Molecular Dynamic were conducted in this paper to investigate the loading, adsorption and diffusion characteristics of CH4, CO2, and N2 in micropores and mesopores. Three micropore models (0.5, 1 and 2 nm) and two mesopore models (5 and 8 nm) were established to study the microscopic mechanism of three gases loading, adsorption and diffusion. The results shown that the loading amounts in pore models increased with increasing pore size. However, the tight adsorption amounts and adsorption heats decreased with increasing pore size. The tight adsorption amounts, loading amounts and adsorption heats all followed CO2 > CH4 > N2. There were exponential changes between isometric heats and loading amounts. The diffusion characteristic of three gases in the pores was CH4 > N2 > CO2, and the larger pores were more conducive to gas diffusion. Radial Distribution Function was implemented to study the action radius between gases and C atoms of coal molecules. There was the smallest effective distance and the largest effective radius between CO2 and C atoms. The action distance between N2 and C atoms was the largest, and the action scope between them was the smallest.
ISSN:0016-2361
1873-7153
DOI:10.1016/j.fuel.2021.120268