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. Studying the growth of sH hydrate is critical for its use. Therefore, massive microsecond-long molecular dynamics simulations were performed in this work to investigate the growth mechanism of sH hydrate with the help of a soluble guest, methane-1-methylpiperidine (MPD). The impacts of temperature, pressure, and guest concentration on the growth processes were also evaluated. By tuning the simulation conditions, we observed the continuous growth of sH hydrate. The results show that the slow crystal growth of sH hydrate is mainly due to the unproper trapping of MPD molecules at the hydrate surface. Neither high nor low temperature is conducive to continuous growth of hydrates. Increasing pressure can greatly promote hydrate growth, however, sI and sII hydrates can cross-grow in the system when the pressure exceeds 50 MPa. In addition, our simulations show that neither too high nor too low MPD concentrations are favorable for the growth of sH hydrate. Our results are useful for designing efficient large-cage guests for storage and transportation of gases in the form of sH hydrate.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the growth mechanism of sH hydrate through large-scale molecular dynamics simulations and finds that the improper trapping of MPD molecules at the hydrate surface is the main cause of slow crystal growth. Increasing pressure promotes hydrate growth, but excessive pressure leads to cross-growth of different types of hydrates. Furthermore, the proper concentration of MPD is also crucial for the growth of sH hydrate.