Molecular dynamics simulations on dissociation of CO2 hydrate in the presence of inhibitor

Abstract

The dissociation kinetics of CO2 hydrate are investigated by molecular dynamics (MD) simulation in the presence of thermodynamic inhibitor glycine (5 wt%, 10 wt%, 15 wt%, 20 wt%) and kinetic inhibitor glucose (1.2 wt%, 2.0 wt%, 3.8 wt%). The molecular dynamics simulations are performed at 273.15 K and 3 MPa under the isothermal-isobaric (NPT) ensemble. The configuration, radial distribution functions, mean square displacement, and density are analyzed respectively. It is found that the dissociation rate of CO2 hydrate is increased in the presence of two inhibitors. The optimal concentration of glycine is 10 wt% and that is 1.2 wt% for glucose. The results indicate different mechanisms for two inhibitors. Glycine accumulates on the solid–liquid surface of the initial structure, and the clathrate hydrate structure is destroyed due to the aggregation of hydroxyl (OH) and amidogen (NH2) with water hydrogen bond in the hydrate structure. While glucose accelerates the dissociation of hydrates because of the synergistic effect of steric hindrance, owing to its ring-shaped structure and the disruption of functional groups.