Experimental and molecular dynamics studies of zwitterionic inhibitors of methane hydrate dissociation

Abstract

Hydrate dissociation inhibitors can be widely applied in the field of natural gas exploitation. A combined experimental and molecular dynamics study into a new type of hydrate dissociation inhibitor is presented herein. The polymeric kinetic inhibitor is zwitterionic and was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. When evaluated by methane hydrate formation and dissociation tests, the zwitterionic compound showed an inhibitory effect on hydrate dissociation of up to 37.3%. A kinetic model for the hydrate dissociation process in the presence of hydrate dissociation inhibitors was validated by the experimental data. The difference in dissociation efficiency can be represented by the methane diffusion coefficient in the liquid phase. Molecular dynamics simulations were performed to investigate the effect of the inhibitor on methane hydrate and water molecules. The results showed that the charged functional groups improved the interaction energy between the inhibitor and methane hydrate through Coulomb interactions, and the sulfonate group had a strong hydration ability, which could affect the distribution of water molecules in the water phase. The molecular-level understanding of the dissociation inhibition mechanism is instructional for the design of new and effective hydrate dissociation inhibitors.