Production of Methanol and Butyl Acetate by Reactive and Extractive Distillation Using Ionic Liquids as Entrainer and Catalyst
|Keywords||Ionic Liquid Vapor-Liquid Equilibium Kinetics Reactive andExtractive Distillation|
Transesterification is widely used in industrial process, and the transesterification of methylacetate and n-butanol in a reactive and extractive distillation column using ionic liquids asentrainer and catalyst （RED-IL） was studied. The effects of ionic liquids on azeotropic systems ofmethanol+methyl acetate and n-butanol+n-butyl acetate, and the kinetics of transesterificationreaction catalyzed by IL were investigated. The process of RED-IL was also simulated byCHEMCAD.The vapor-liquid equilibrium （VLE） of methanol+methyl acetate+1-octyl-3-methylimidazolium hexafluorophosphate （[OMIM][PF6]）, and VLE and liquid-liquidequilibrium （LLE） of n-butanol+n-butyl acetate+[OMIM][PF6] were measured. The resultsshow that [OMIM][PF6] can enhance the relative volatility of methanol to methyl acetate andn-butanol to n-butyl acetate notablely. Both VLE and LLE data were correlated by NRTL model,and the calculated results agree well with the experimental ones.The kinetics of the transesterification of methyl acetate and n-butanol catalyzed by IL1-sulfoacid butyl-3-methylimidazolium bisulfate （[HSO3-bHim]HSO4） was investigated. Twodifferent kinetic models, the ideal homogeneous （IH） model and the nonideal homogeneous （NIH）model, were used to correlate the kinetic data. The NIH model was able to describe the reactionrate reliably. The ionic liquid catalyst was compared with the conventional inorganic acid andion-exchange resin catalysts sulfuric acid and Amberlyst15, and it was found to be more activethan the two conventional catalysts.A reactive and extractive distillation process was proposed to produce methanol and n-butylacetate from methyl acetate and n-butanol, using IL [OMIM][PF6] and [HSO3-bHim]HSO4asentrainer and catalyst, respectively.The RED-IL process was simulated by CHEMCAD, and high purity products of methanol andn-butyl acetate can be obtained in such a process. The effects of reflux ratio, feed mode, holdup,feed location, entrainer ratio and catalyst concentration on RED-IL process were investigated. Thepurities of products increase with the holdup in the column, entrainer ratio and catalyst content. Anoptimal reflux ratio exists in RED-IL process. Comparing to the mixed-feed mode, thesegregated-feed mode is more effective, in which the optimal feed locations of reactants exist.