外文文献翻译：用混合溶剂萃取精馏分离乙腈-乙酸乙酯

Separationofacetonitrile-ethylacetatebyextractivedistillationwithmixedsolventLiChunli1,ZongLili2andFangJingSchoolofChemicalEngineering,HebeiUniversityofTechnology,Tianjin,30013E-mail:[e-mail],Tel:[phone]AbstractComputer-aidedmoleculardesign(CAMD)approachwasbringinthisworkforselectingextractivesolvents.Theseparationofacetonitrile-ethylacetateAzeotropicsystemwascarriedoutthroughabatchextractivedistillationprocesseswithN,N-dimethylformamide(DMF),glycol(EG)andDMF-EGmixtureassolventsseparately.Theeffectsofdifferentoperatingconditionswerestudied,solvents,ratioofmixedsolvent,solventflowrateandrefluxratiowereallincluded.ItwasfoundthatthemixedsolventDMF-EGshowedbetterseparationeffectthanthesinglesolvent.Thebestproportionofthemixedsolventwas3:7(thequalityofDMFandEG);whenthesolventflowrateandrefluxratioincreased,theseparationeffectofmixedsolventimproved;undertheconditionsthatsolventflowratewas20mL/min,refluxratiowas2,qualityfractionofethylacetateinthetopproductcouldreach99.62%.KeywordsSeparation;Batchextractivedistillation;Mixedsolvents;Acetonitrile;Ethylacetate1.IntroductionAcetonitrileandethylacetatearewidelyusedinchemicalandpharmaceuticalindustriesaschemicalrawmaterialsandgoodorganicsolvent[1].Butthetwoformazeotrope,ethylacetatehold77%andtheother23%isacetonitrile(massfraction),commondistillationmethodcannotmakeanyeffect.Therefore,somecompanieshavetotreatthemaswaste,thisnotonlycauseseriouslywasteofresourcesandeconomy,butalsopollutetheenvironment.Atpresent,DiJiandong[2]ofTianjinuniversityhasrealizedtheseparationofacetonitrile-ethylacetatebyheterogeneousbatchazeotropicdistillation,buttheproductreceivedinthiswayhavelowerpurity,buthighenergyconsumption.Accordingtothedifferenceofsolubilitythatacetonitrileandethylacetateinthewater,MaWenchan[3]adoptsthemethodofliquid-liquidextractivewhichusewaterasextractiveagenttoseparateacetonitrile-ethylacetate,theproductofethylacetatecanachieve98.5%,butacetonitrilemixedwithabundantwater,sorecoveryofacetonitrileisverydifficult.Accordingtoourknowledge,noauthorshavestudiedtheseparationofacetonitrile-ethylacetatebyextractivedistillation.Inrecentyears,theapplicationofextractivedistillation[4-6]fortheseparationofclose-boilingmixturehasbeenwidelyacceptedandcommercializedovertheconventionaldistillationwhichmayalsobefeasiblebutwithsubstantialcolumninvestment.However,duetotheproblemofselectivityandsolubilityareofteninconsistentinsinglesolvent,limititsapplicationanddevelopment.Mixedsolventsguaranteehighselectivity,andimprovedsolubilityatthesametimethroughthecombinationofmainsolventandvicesolvent[7].Inrecentyears,mixedsolventsareappliedmoreandmoreinextractivedistillation[8-11].Thispaperisdevotedtothestudyoftheseparationofthemixtureacetonitrile–ethylacetatebyusingextractivebatchdistillationwhichextractivesolventismixedsolvents.First,theselectionofanadequateextractivesolventispresentedbasedonthecomputeraidedmoleculardesignofsolventsforseparationprocessescombininggroupcontributionmethodswithgraphprinciple.Later,resultsofseverallaboratorybatchtestsarepresentedservingfordeterminationofthemosteffectivesolvent.Finally,themainoperatingparametersofextractivedistillationprocesswereoptimized.2.Entrainerselectionfortheseparationofacetonitrile–ethylacetatemixtureTheextractivedistillationisgenerallyappliedtotheseparationofclose-boilingmixtures,whichbyconventionaldistillationisdifficulttoseparate.Thedesignandoptimizationofextractivedistillationismorecomplexthanthatoftheconventionaldistillationwhenconsideringtheselectionofsuitablesolventtoenhancetheseparation.Intheextractivedistillation,theselectionofasuitablesolventisfundamentaltoensureaneffectiveandeconomicaldesign.Currently,thesolventselectioncanbeeffectivelyhandledbytheassistanceofthecomputer-aidedmoleculardesign(CAMD)approach.Thecandidatesasextractivesolventwerechosenbythegraphprincipleandgroupcontributionmethodcombinedwithcomputer-aidedmoleculardesign.Firstly,basedonModfiedUNIFACmethod,thefunctionalgroupssystematicallyareclassifiedandpre-selectedaccordingtosomerules,andthentheautomaticcombinationofgroupsiscompletedbyusingagraphalgorithm.Thegroupcontributionmethodsareusedtogetthebasicphysicalandthermalproperties.Thebasicmolecularlibraryisformedbyusingseverallimitedrulesofbasicphysicalproperties.Inthestageofsolventscreening,themoleculesinthebasicmolecularlibraryareuseddirectly.Thecandidatesolventmoleculesareobtainedbyusingthesolventconstraintandtheappropriatesolventmoleculescanbedeterminedbyusingtherefinedcalculationorcheckingpropertylibrary.Accordingtotheabovemethod,wegotsomecandidatesolventsthroughthegraphprincipleandgroupcontributionmethodcombinedwithcomputer-aidedmoleculardesign.AftercautiouslyselectedweobtainedDMFandEGassolventswhicharethemostappropriatefortheseparationofacetonitrile–ethylacetate.3.Experimentsuppliesoftheextractivedistillation3.1MaterialsThecomponentmassfractionofacetonitrile–ethylacetaterawmaterialis0.77/0.23(ethylacetate/acetonitrile).ThepurityofDMFis0.995(massfraction).ThepurityofEGis0.995(massfraction).3.2Equip