The separation of methanol (MeOH) and dimethyl carbonate (DMC) is important but difficult due to the formation of an azeotropic mixture. In this work

isobaric vapor-liquid equilibrium (VLE) data for the ternary systems containing different imidazolium-based ionic liquids (ILs)

i.e

. MeOH + DMC + 1-butyl-3-methy-limidazolium bis[(trifluoromethyl)sulfonyl

]

imide ([Bmim

]

[Tf

2

N

]

)

MeOH + DMC + 1-ethyl-3-methyl-imidazolium bis [(trifluoromethyl)sulfonyl

]

imide ([Emim

]

[Tf

2

N

]

)

and MeOH + DMC + 1-ethyl-3-methylimidazolium hexafluorophosphate ([Emim

]

[PF

6

]

)) were measured at 101.3 kPa. The mole fraction of IL was varied from 0.05 to 0.20. The experimental data were correlated with the NRTL and Wilson equations

respectively. The results show that imidazolium-based ILs were beneficial to improve the relative volatility of MeOH to DMC

and [Bmim

]

[Tf

2

N

]

showed a much more excellent performance on the activity coefficient of MeOH. The interaction energies of system components were calculated using Gaussian program

and the effects of cation and anion on the separation coefficient of the azeotropic system were discussed.