Revealing the Growth Mechanism of Sh Hydrate by Molecular Simulations

Clathrate hydrates are considered efficient materials for gas storage and transportation: sH hydrate is one of the promising candidates. Research on the growth of sH hydrate is critical for its use. In this study, molecular dynamics simulations were performed to investigate the growth mechanism of the methane–1-methylpiperidine (MPD) sH hydrate. The influences of temperature, pressure, and MPD concentration were evaluated. The results show that the growth of sH hydrate is mainly controlled by the MPD molecules, where their adsorption and migration at the hydrate–solution interface are key factors. High temperature is not conducive to continuous growth of hydrates due to instability of the water cages. To the best of our knowledge, this study is the first time to observe continuous growth of sH hydrate in a long-term molecular dynamics simulation. Increasing pressure can greatly promote hydrate growth. sI and sII hydrates can grow in the system when the pressure exceeds 50 MPa. Our simulations indicate that too high or too low concentrations of MPD are not conducive to growth of sH hydrate. These results are useful for designing efficient large-cage guests for storage and transportation of gases in the form of sH hydrate