Synthesis Of Isobutyl Acetate Via Reactive And Extractive Distillation

In recently years,an obvious trend of the chemical industrial is to realize green production with energy saving and consumption reducing.Ionic liquid has a low melting point and high boiling point with neglected vapor pressure,and it also has good solubility and excellent catalytic performance,so it can be used in energy saving and environment protection process.Reactive and extractive distillation(RED)process,which integrates the reactive distillation and the extractive distillation into one equipment,can improve reaction conversion and selectivity,reduce energy and equipment cost.In this paper,transesterification of methyl acetate with isobutanol in a reactive and extractive distillation column with ionic liquid 1-sulfobutyl-3-methylimidazolium hydrogensulfate([HSO3bmim][HSO4])as catalyst and molecular liquid o-xylene(OX)as entrainer was investigated.Firstly,the effects of catalyst and entrainer on the vapor-liquid equilibrium of the two azeotropes of methanol-methyl acetate and isobutanol-isobutyl acetate were analyzed respectively.The results indicate that the catalyst has a negative impact on the process,so suitable amount of catalyst should be used in the reactive and extractive distillation process.The entrainer o-xylene is effective,and azeotropic points can be eliminated by enough amount of entrainer.The kinetics of the reaction system was measured,in addition,the influences of different reaction conditions were also discussed.Based on the reaction mechanism,ideal homogeneous(IH)model and nonideal homogeneous(NIH)model were adopted to correlate the reaction kinetic data,and the corresponding kinetic parameters were obtained.The NIH model was more reliable to describe the reaction rate.The feasibility of the reactive and extractive distillation process was analyzed by the analysis of the reactive residual curve maps.Secondly,the process of transesterification of methyl acetate with isobutanol via reactive and extractive distillation was developed and simulated.The simulation results indicated that high purities of methanol and isobutyl acetate were obtained.The sensitivity analysis showed that there were optimal reflux ratio,feed location of entrainer-catalyst,and catalyst concentration in the RED column.For the ER column,the purity of isobutyl acetate and the concentration of entrainer + catalyst increased with the number of theoretical stages and reflux ratio.There was also an optimal feed location in ER column.Lab-scale experiments were carried out,and the experimental results agreed well with the simulation results,which indicated that the RED process was feasible and the simulation results were reliable.Lastly,the RED process and reactive distillation(RD)were,respectively,optimized with the total annual cost(TAC)as objective function,and the optimal operation and structure parameters were obtained.Comparing the results of RED process with those of RD process under optimal parameters,the energy consumption and TAC of the RED process were less than those of RD process.