外文文献翻译：用混合溶剂萃取精馏分离乙腈

Separationofacetonitrile-ethylacetatebyextractive

distillationwithmixedsolventLiChunlil,ZongLili2andFangJing

SchoolofChemicalEngineering,HebeiUniversityofTechnology,Tianjin,30013

E-mail:,Tel:+86-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.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.Experimentsuppliesoftheextractivedistillation3.1MaterialsThecomponentmassfractionofacetonitrile-ethylacetaterawmaterialis0.77/0.23(ethylacetate/acetonitrile).ThepurityofDMFis0.995(massfraction).ThepurityofEGis0.995(massfraction).3.2EquipmentBatchexperimentswerecarriedoutinasmalllaboratorycolumntoevaluatethefeasibilityofthenewsolvent.Theglasscolumnhasatotalheightof1.8mandaninternaldiameterof30mm.Itispackedwithstainlesssteel9-ringsof3mmx3mm.Thetotalpackedheightisabout1.5m.Thebottomisa1500mlflaskwithopening.Thesolventisfeedtothecolumnfromthetopsection.Theflowrateiscontrolledbyarotameter.Therefluxratioisprovidedatthetopofthecolumnbyasolenoidvalve.ThesketchmapisshowedinFig.1.ResultsanddiscussionInordertoillustratetheeffectofthenewsolventtoacetonitrile-ethylacetate,wedosomeexperiencetoinvestigatethetechnologicalparameters,andreceiveoptimizedoperationconditions.4.1EffectsofdifferentsolventTheeffectsofdifferentsolventontheconcentrationofethylacetateinthetopproductwereshowedinFig.2.Todothis,someconditionsweremaintained:solventflowratewas15mL/min,solventratio(massratioofsolventtotheproduct)was4.0,refluxratiowas1,n(DMF)：n(EG)=1:1inthemixedsolvent(DMF:N,N-dimethyformamideEG:ethyleneglycol).Fig.2showsthatthethreesolventsallhasthefunctionofincreasetheconcentrationofethylacetateinthetopproduct,Destroytheazeotropiccomposition.WhenthesolventisDMForEGonly,theconcentrationofethylacetateinthetopproductwillbe90.4%and93.9%,respectively.Butwhenusen(DMF)n(EG)=1:1assolvent,theconcentrationwillincreaseto97.7678%,theeffectobviouslysuperiortothesinglesolvent.ThisduetocombinationofthestrongsolubilityofDMFandtheefficientselectivityofEG.Theycomplementandpromoteeachother,sothemixedsolventrevealsbettereffectontheconcentrationofethylacetatethansinglesolvent.Therelativevolatilityofacetonitrile-ethylacetatewaschangedinalargeextent,sothattheseparationefficiencyimprovedandthepurityofproductincreased.4.2EffectsofmixedsolventswithdifferentratioTheeffectsofmixedsolventwithdifferentratioontheconcentrationofethylacetateinthetopproductareshowedinFig.3.Similarly,todothis,someconditionsweremaintained:solventflowratewas15mL/min,solventratio(massratioofsolventtotheproduct)was4.0refluxratiowas1.WecanseefromFig.3thatwhilethethecontentofDMFinmixedsolventincrease,theconcentrationofethylacetateinthetopproductincreasefirstandthendecrease,andwhenthecontentofDMFwas30%,theethylacetateownthehighestconcentrationthatis98.3104%.WhenthecontentofDMFinmixedsolventlowerthan30%,themainsolventEGensuretheselectivityofthemixedsolvent,butaddedofDMFimprovedthesolubilityofthemixedsolvent,soshowbettereffect.WhenthecontentofDMFinmixedsolventhigherthan30%,theselectivityofEGdecreasedgradually,sotheeffectofthemixedsolventwasweakened.Accordingtothesedata,wethinkthemixedsolventthatDMF/EG=3/7wasthebest.4.3EffectsofsolventflowrateTheeffectsofsolventflowrateontheconcentrationofethylacetateinthetopproductareshowedinFig.4.Intheaboveconditionsthatbeoptimized,weinvestigatedtheeffectontherefluxratioontheconcentrationofethylacetateinthetopproduct.Fromthelinechartwefindthattheconcentrationofethylacetateinthetopproductincreasewiththeincreaseofrefluxratio,whiletherefluxratioexceed2,thepurityoftheproductwillalmostconstant.Ontheotherhand,exceedrefluxratiowillbringsomeproblems,suchasextendoperationtime,energyneededinthetowerbottomincrease,influenceproductionefficiencyandsoon.Soweshoulddecreasetherefluxratiointhepremiseofqualityassurance.Inthatcase,wechose2assuitablerefluxratio.ConclusionWegotDMFandEGascandidatesolventsforacetonitrile-ethylacetateseparationthroughthegraphprincipleandgroupcontributionmethodcombinedwithcomputer-aidedmoleculardesign.Theeffectofthesolventwasillustratedbyexperiment.FromtheresultwecanseethatmixedsolventDMF-EGhasalotofadvantagethansingleDMForEGsolvent.Throughtheexperimentsweobtainedtheoptimizedoperationparameters:theratioofmixedsolventDMF/EG=3/7,flowrateofthemixedsolventwas20mL/min,therefluxratiowas2.ReferencesChengNenglin.Solventshandbook[M].Beijing:ChemicalEngineeringPress.2002.DiJiandong.Studyonseparationofacetonitrileandethylacetatemixturebybatchazeotropicdistillation[D].Tianjin.TianjinUniversity,2006.MaWenchan,SunJianjie.Studyonseparationofacetonitrileandethylacetatemixturebyextractivedistillation.ApplicationChemical.2010,39(5):781-782.R.VanKaam,I.Rodrguez-Donis,V.Gerbaud.Heterogeneousextractivebatchdistillationofchloroform-methanol-water:Feasibilityandexperiments.ChemicalEngineeringScience.2008,63(1):78-94JingFANG,ChunliLI,HonghaiWANG,LijunSUN.AQuasi-steady-stateModelforNumericalSimulationofBatchExtractiveDistillationOriginalResearchArticle.ChineseJournalofChemicalEngineering.2010,18(1):43-47EstelaLladosa,JuanB.Monton,MaCruzBurguet.Separationofdi-n-propyletherandn-propylalcoholbyextractivedistillationandpressure-swingdistillation:Computersimulationandeconomicoptimization.ChemicalEngineeringandProcessing:ProcessIntensification.2011,50(11-12):1266-1274LeeFM,BrownRE.Extractivedistillationofhydrocarbonmixtureemployingmixedsolvent[P].US:4954224,1990-09-04.PaulLangston,NidalHilal,StephenShingfield,SimonWebb.Simulationandoptimisationofextractivedistillationwithwaterassolvent.ChemicalEngineeringandProcessing:ProcessIntensification.2005,44(3):345-351LiChunli,SunJingjing,LvJianhua.Studyonmixedsolventforseparatingethanolandwaterbyusingbatchextractivedistillation.ChemicalEngineeringChina.2011,39(10):29-33LiChunli,LiLijie,FangJing.Separationofethylacetate-ethanolbybatchextractivedistillationwithmixedsolvent.PetrochemicalTechnology.2010,39(11):1232-1235Guzhenggui,ZhiHuizhen,MaZhengfei.Studyoncompositeextractivedistillationofethylacetate-ethanol-water.ComputApplChem,2005,22(6):466-468LangF,LelksZ,MoszkowiczPBatchExtractiveDistillation:TheProcessandtheOperationalPolicies.ChemicalEngineeringScience,1998,53(7):1331-1348.用混合溶剂萃取精馏分离乙腈-乙酸乙酯摘要计算机辅助分子设计（CAMD）方法是把在这项工作中选择萃取溶剂。乙月青-乙酸乙酯共沸体系的分离是通过一批进行萃取精馅过程与N，N-二甲基甲酰胺（DMF），乙二醇（EG）和dmf-eg混合物溶剂分别。不同的操作条件的影响进行了研究，溶剂，混合溶剂的配比，溶剂流量和回流比均包括。结果发现，混合溶剂dmf-eg表现出更好的分离效果比单一溶剂。混合溶剂的最佳比例为3:7（DMF质量和EG）；当溶剂流量和回流比的增加，混合溶剂的分离效果改进的；的条件下，溶剂的流速为20毫升/分钟，回流比为2,质量分数在产品乙酸乙酯可以达到99.62%。关键词间歇萃取精馅分离；；混合溶剂；乙月青；乙酸乙酯1引言乙青和乙酸乙酯广泛应用于化工、医药等行业为化工原料材料和良好的有机溶剂［1］。但两种形成共沸物，乙酸乙酯持有77%和另23%是乙青（质量分数），普通精馅方法不做任何的效果。因此，一些公司要把他们当作废物，这不仅造成严重的资源浪费和经济，而且还污染环境。目前，翟建［2］天津大学实现了分离乙青-乙酸乙酯由异质批次共沸蒸偶醋，但收到的产品以这种方式具有较低的纯度，但高能耗。根据溶解在乙青和乙酸乙酯的差异水，马汶川［3］采用液-液萃取使用水作为萃取剂的方法分离乙青-乙酸乙酯，乙酸乙酯产品可以达到98.5%，但与乙青混合丰富的水，所以乙青的回收是很困难的。据我们所知，没有了乙青萃取精馅分离乙酸乙酯。近年来，应用萃取精馅［4-6］对近沸点混合物的分离已被广泛接受商业化在传统的蒸偶，也可能是可行的但有大量的柱投资。然而，由于对选择性与溶解性问题往往是在单一溶剂不一致，限制了它的应用与发展。混合溶剂中，保证高选择性，和改进的溶解度在同时通过主溶剂、副溶剂［7］的组合。近年来，混合溶剂萃取精馅过程［8-11］越来越多的应用。本文用乙青的混合物-乙酸乙酯的分离研究间歇萃取精馅，萃取溶剂的混合溶剂。首先，一个适当的选择溶剂萃取是基于溶剂的计算机辅助分子设计分离了流程图原理相结合的基团贡献法。后来，几个实验室分批结果测试是为最有效的溶剂的测定。最后，主要经营萃取精馅的工艺参数进行了优化。2.乙青的-乙酸乙酯混合物分离夹带剂的选择萃取精馅是普遍适用于近沸点混合物的分离，由传统的精馅分离困难。与萃取精馅优化设计比较比常规蒸馅时考虑合适的溶剂，提高选择的复杂分离。在萃取精馅，合适的溶剂的选择是根本保证有效和经济的设计。目前，溶剂的选择可以借助有效的处理计算机辅助分子设计（CAMD）的方法。候选作为萃取溶剂的图原理与基团贡献方法的选择结合计算机辅助分子设计。首先，基于改UNIFAC法，功能组分和预先选定的系统根据一定的规则，然后自动结合组用图算法完成。基团贡献的方法被用来获得基本物理性能和热性能。基本的分子库是通过使用几个有限的规则的形成基本物理性能。在溶剂筛选阶段，用于基本的分子库的分子直接。采用溶剂约束和相应的得到候选溶剂分子溶剂分子可以通过精确的计算和校验性能库确定。根据上述方法，我们得到了一些候选溶剂通过图的原则和组贡献法结合计算机辅助分子设计。经过慎重选择我们得到的如DMF和溶剂是最合适的用于乙腈-乙酸乙酯的分离。3的萃取精馏实验用品3.1材料乙月青-乙酸乙酯原料成分的质量分数为0.77/0.23（乙基醋酸乙烯/乙月青）。DMF纯度为0.995（质量分数）。EG的纯度为0.995（质量分数）。3.2设备批实验是在一个小的实验室柱评价新的可行性进行了溶剂。玻璃柱总高度1.8米，内部直径30mm。这是挤满了不锈钢。-3毫米3毫米x环。总的填料高度约150万。底部是一个1500毫升瓶与开放。溶剂是饲料从上节柱。的流量由流量计控制。回流比是通过电磁阀柱的顶部设有。示意图显示在图1。4.结果与讨论为了说明新的溶剂效应对乙腈-乙酸乙酯，我们做的一些经验研究了工艺参数，得到优化的操作条件。不同的溶剂4.1effects在不同溶剂中的顶级产品乙酸乙酯的浓度的影响表现在图2。为此，一些条件下保持：溶剂流速为15ml/min，溶剂比（质量比溶剂对产品）为4，回流比为1,n（DMF）:n（EG）=1:1的混合溶剂（DMF：N，N—二甲基甲酰胺；例如：乙二醇）。图2显示三溶剂都有增加的功能在产品乙酸乙酯浓度，破坏共沸组成。当溶剂DMF或如只在顶级产品，乙酸乙酯的浓度是90.4%和93.9%，但当使用N（DMF）：n（EG）=1:1作溶剂，浓度增加到97.7678%，效果明显优于单一溶剂。这是由于DMF的强溶解性组合和高效的选择性他们相互补充、相互促进，从而揭示了在混合溶剂的浓度的效果更好乙酸乙酯比单一溶剂乙月青。-乙酸乙酯相对波动是在一个大的改变程度，使分离效率提高，产品的纯度提高。用不同比例的混合溶剂4.2以不同配比对产品顶部的乙酸乙酯混合溶剂的浓度的影响显示在图3。同样，要做到这一点，一定条件下保持：溶剂流速为15ml/min，