Methane Behavior in Carbon Nanotube as a Function of Pore Filling and Temperature Studied by Molecular Dynamics Simulations

• Published in: Journal of physical chemistry. C 2017-02, Vol.121 (7), p.4066-4073
• Main Authors: Bartuś, Katarzyna, Bródka, Aleksander
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.6b12855

We report structural and dynamic properties of methane inside the (15,15) carbon nanotube (CNT) obtained from molecular dynamics simulations of flexible methane molecules, and intramolecular interactions are introduced by the reactive empirical bond order potential. The calculations are performed for a wide range of temperatures and loadings that correspond to states from the dense gas phase to the liquid state. The properties of flexible and rigid models of methane molecules are compared. The diffusivity of molecular translations along the CNT and rotations increase with temperature, and they decrease with pressure. Temperature dependences of the diffusion coefficients for flexible molecules are predicted by the Arrhenius equation. Internal motions of the CH4 atoms diminish the activation energies of the translational diffusion and increase the energies of the rotational diffusion, especially for higher pressures. The results mean that the possibility of changes of molecular bond lengths and valence angles in methane molecules causes a reduction of hindrances of their translations and at the same time it leads to the increase of rotational motion interruptions.