Isobaric vapor-liquid equilibria for the isobutanol-water-1-butyl-3-methylimidazolium tetrafluoroborate ternary system

Isobaric vapor-liquid equilibrium data for the isobutanol-water system containing the ionic liquid(IL) 1-butyl-3-methylimidazolium tetrafluoroborate([BMIM]BF4) were measured in a modified Othmer still at 101.32kPa.The vaporliquid equilibrium curve for the isobutanol-water with added IL deviates from that of the binary system when the mole fraction of BF4 reaches 10%.When the mole fraction of BF4 is 20% or 30%,the deviation is greater.The IL shows a salt effect,which increases the volatility of isobutanol relative to that of water,and even leads to the disappearance of the azeotropic point.Increasing addition of BF4 results in the salt effect becoming more distinct,and the volatility of isobutanol relative to water increases.As a result,it is concluded that BF4 can be employed as a salt in the extractive distillation of the isobutanol-water system.The optimum mole fraction of [BMIM]BF4 is about 20%,and the VLE data obtained allow the design of the process to be optimized.