  The thermo-kinetic inhibition mechanism of six imidazolium-based ionic
liquids (ILs) on methane clathrate hydrate formation and growth is studied in
this work using classical molecular dynamics (MD) simulation. The ionic liquids
investigated include
1-(2,3-dihydroxypropyl)-3-methylimidazoliumbis(fluorosulfonyl)imide
([C3(OH)2mim][f2N]), 1-(2-hydroxyethyl)-3-methylimidazolium
bis(fluorosulfonyl)imide ([C2OHmim][f2N]), 1-ethyl-3-methylimidazolium
tetrafluoroborate ([C2mim][BF4]), 1-butyl-3-methylimidazolium tetrafluoroborate
([C4mim][BF4]), 1-butyl-3-methylimidazolium acetate ([C4mim][OAc]) and
1-ethyl-3-methylimidazolium ethylsulfate ([C2mim][EtSO4]). Simulations showed
that [C2OHmim][f2N] and [C3(OH)2mim][f2N] are strongly hydrated compared to
other ILs because of hydrogen bonding between OH groups of the cation and water
molecules. They also exhibit high diffusion rates towards crystal surface and
bond to it through strong intermolecular interactions. As a result, these two
ILs are stronger thermo-kinetic inhibitors for formation and growth of methane
hydrates compared to other ILs studied in this work as well as conventional
inhibitors like methanol and NaCl. The simulations also revealed that cations
of [C3(OH)2mim][f2N] and [C2OHmim][f2N] show that the presence of ions near the
hydrate crystal causes hindrance for water and guest molecules adsorbing on the
hydrate surface, which inhibits the growth of hydrate crystals. In addition, it
is shown that [C3(OH)2mim][f2N] and [C2OHmim][f2N] are more likely to inhibit
hydrate formation.
