Ionic Liquids Used In The Study Of Separation Of Methanol And Dimethyl Carbonate

Extractive distillation is commonly used in the separation of methanol and dimethyl carbonate in the industry. The selection of extraction solvents is the key in extractive distillation, but traditional organic solvents are easily volatile and have great toxicity. Four kinds of ionic liquids (ILs),1-methyl-3-methylimidazole dimethylphosphate ([MMIM][DMP]),1-ethyl-3-methylimidazole diethylphosphate ([EMIM][DEP]),1-buty1-3-methyl imidazole dibutylphosphate ([BMIM][DBP]),1-buty1-3-methylimidazole acetate ([BMIM][OAc]) was selected as extraction solvents in this work, isobaric vapor-liquid equilibrium (VLE) data for binary and ternary system is measured to research the feasibility of ILs in separating methanol and dimethyl carbonate using extractive distillation. Main work as follows:1.[MMIM][DMP],[EMIM][DEP],[BMIM][DBP],[BMIM][OAc] ILs were synthesized according to the published method; the purity and water content of the ILs were measured by1H-NMR analysis and Karl Fischer method respectively, the results showed that ILs synthesized met experimental demand. 2. Isobaric vapor-liquid equilibrium data for binary and ternary systems are measured by using a vapor-liquid equilibrium still (CE-2) to determine the effect of ILs on the vapor-liquid equilibrium curve of methanol and dimethyl carbonate. The research results show that the activity coefficient of methanol decreases along with the concentration of ILs in the liquid phase while the activity coefficient of dimethyl carbonate increases; the decrease of methanol activity coefficient follows the order:[MMIM][DMP]<[EMIM][DEP]<[BMIM][OAc]<[BMIM][DBP]; the increase of dimethyl carbonate activity coefficient follows the order:[BMM][DBP]<[EMIM][DEP]<[MMIM][DMP]<[BMIM][OAc]; the azeotropic point of methanol and dimethyl carbonate can be totally eliminated by ILs used; the effect of separating methanol and dimethyl carbonate using ILs follows the order:[BMIM][DBP]<[EMIM][DEP]<[MMIM][DMP]<[BMIM][OAc].3. The vapor-liquid equilibrium data are correlated by the electrolyte nonrandom two-liquid (e-NRTL) model, and the maximal relative deviations is4.9%for binary systems, and4.3%for ternary systems, which shows that the e-NRTL model correlates successfully with the experimental data.4. Extractive distillation process simulations of methanol and dimethyl carbonate are carried out for selecting [BMIM][OAc] as extraction solvent in Aspen Plus software, and the optimized operation condition parameters can provide a reference basis for separation of methanol and dimethyl carbonate using [BMIM][OAc]. The research results show that the ILs of selection are potential extraction solvent for the separation of methanol and DMC using extractive distillation.