Molecular Dynamics Investigation on the Adsorption of Coalbed Methane Utilizing Carbon Nanotubes under the Condition of Liquid Water

Abstract

The carbon nanotubes(CNTs) was described according to condensed-phase optimized molecular potentials and arranged to represent coal structures, while interaction of CNTs with gas components of the system involves the Van der Waals force. Thus, we are able to study the interaction ability between coal and gas in different cases through the binding energy calculated by molecular dynamic method. We find that when there was not liquid water, the adsorption capacity of coal bed methane gases on the surface of CNTs, in the order of magnitude, was CO2>CH4>N2, and when there existed liquid water, the order of the adsorption capacity of gases changed into the order of N2>CH4>CO2>H2O. When there existed liquid water, the surface of CNTs may first absorb a very thin layer of methane molecules, and then a layer of water group, forming a layer of water film or water drops, providing large quantity of adsorption potential for the residual gases.

Molecular Dynamics Simulation of Methane Adsorption and Diffusion: A Case Study of Low-Rank Coal in Fukang Area, Southern Junggar Basin

“…Molecular simulation is widely used to construct the molecular structure of coal and study the mechanism of coal and methane interaction at the microscopic level [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. To optimize gas production from coal reservoir rocks, an understanding of diffusion kinetics is a prerequisite [26].…”