Isobaric Vapor-liquid Equilibrium For Toluene-methanol System Including Three Ionic Liquids With Acetate Anion At 101.3 KPa

Toluene and methanol are important organic solvents in the fields of medicine and fine chemicals.Azeotrope is formed at one atmosphere,and the azeotropic composition?mol?is 88.2% of methanol and 11.8% of toluene.The formed azeotrope is the lowest azeotrope,and it is difficult to separate it by ordinary rectification.At present,the extractive distillation technology is relatively mature.If a suitable extractant can be found,the extractive distillation technology will be greatly developed in the separation direction.Ionic liquids have attracted extensive attention as green organic solvents.The use of ionic liquids instead of traditional organic solvents for extractive distillation of toluene-methanol azeotrope systems is a hot topic.420 ionic liquids composed of a common 20 anions and 21 cations were screened by using COSMOtherm X.Considering their solubility,price and availability,three ionic liquids with acetate anions were selected(1-decyl-3-methylimidazolium acetate [DMIM][OAC],1-tetradecyl-3-methylimidazolium acetate [C₁₄MIM][OAC]and trioctyl methylammonium acetate [N_8,8,8,1][OAC]).The toluene-methanol azeotrope system was separated by ionic liquid with acetate anion.The gas-liquid equilibrium?VLE?data of the binary system?toluene-methanol?and the ternary system were measured under atmospheric pressure.The results showed that all three ionic liquids were obtained.Breaking the azeotropy of the system and significantly increasing the relative volatility of toluene to methanol.When [N_8,8,8,1][OAC] was used as an entrainer,toluene was a heavy component and when [DMIM][OAC] and [C₁₄MIM][OAC] were used as entrainers,toluene was a light component.After the toluene-methanol azeotrope was completely eliminated,the separating ability of [DMIM][OAC] is higher than that of [C₁₄MIM][OAC].The experimental data is consistent with the fitted data of the NRTL model,indicating that the binary and ternary gas-liquid equilibrium data have a good correlation with the NRTL model.The process simulation and sensitivity analysis of Aspen Plus were carried out by separating the toluene-methanol azeotrope system with [DMIM][OAC] as the extractant,and the operating conditions when the purity of the overhead product reached 99.9% were obtained.