Molecular insight into the effect of wettability of solid surface on the methane hydrate formation and dissociation

Abstract

The natural gas hydrate has become one of the most important future green energy sources. The investigation on the influence of sand surface property on gas hydrate formation and dissociation is crucial. However, the impact of solid surface wettability on mechanism of the gas hydrate formation and dissociation has been still unclear. This study performs molecular dynamic simulations on the formation and dissociation of methane hydrate on silica surfaces with various wetting conditions. Simulation results show that hydrophilic SiO₂ surface could enhance hydrate cage stability. The hydrophobic SiO₂ surface competes with hydrate cage to adsorb methane molecules, which facilitates methane hydrate dissociation. Simulation results of hydrate formation reveals that the locally high concentrations of methane dispersed in liquid phase are important conditions for hydrate formation. Methane molecules adsorbed on hydrophobic surface become the methane gas source during hydrate formation process, which could contribute to nucleation and growth of methane hydrate.