Isobaric VLE data for the system of butan-1-ol + butyl ethanoate + 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide

•Vapor–liquid equilibrium (VLE) for the azeotropic mixture with ionic liquid.•The addition of ionic liquid enhanced the relative volatility.•Use the NRTL activity coefficient model to correlate the experimental VLE data.•The correlated results and the experimental data agreed well.

Vapor–liquid equilibrium (VLE) for the ternary system of butan-1-ol + butyl ethanoate + 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([BMIM][NTf2]) and the binary system of butan-1-ol + [BMIM][NTf2], as well as butyl ethanoate + [BMIM][NTf2] were measured at 101.3 kPa. The experimental VLE data were correlated by the nonrandom two-liquid (NRTL) activity coefficient model, and the correlated results agreed well with the experimental data. The results showed that the addition of ionic liquid ([BMIM][NTf2]) to the azeotropic mixture produced a notable salting-out effect, which enhanced the relative volatility of butan-1-ol to butyl ethanoate. The ionic liquid entrainer [BMIM][NTf2] was compared with the conventional entrainer ethylene glycol, and [BMIM][NTf2] is more effective for the separation of the azeotropic mixture of butan-1-ol + butyl ethanoate via extractive distillation.