Combined Molecular Simulations and Experimental Study of Methane Adsorption on Anthracite

摘要

A quantitative characterization of methane (CH4) adsorption on coal with different pressures and temperatures, and a better understanding of the mechanism of the interaction energy and coal swelling is of great significance for the commercial extraction of coal bed methane (CBM). Therefore, CH4 adsorption isotherms of anthracite with temperatures ranging from 273 to 323 K have been simulated and tested. When the pressure increased up to 20 MPa, both the simulated and experimental results showed that CH4 adsorption conforms to the Langmuir model. The interaction energies between anthracite and CH4 markedly increased at first and then slightly decreased with increasing pressure. When the temperature increased to 323 K, CH4 maximum adsorption decreased exponentially, the interaction energies between anthracite and CH4 become more positive and anthracite swelling decreased. The radial distribution function (RDF) results showed that CH4 is strongly adsorbed by the sites of the carbon atoms, followed by hydrogen and nitrogen atoms of anthracite. The results of this study can provide details of the correlation among methane adsorption, interaction energies, and anthracite swelling, and also contribute to the evaluation and extraction of CBM.