Direct
ChineseJournalofChemicalEngineering,16(2)223—227(2008)
;DirectSynthesisofDiphenylCarbonatewithHeterogeneousCatalyst
;andOptimalSynthesisConditionsoftheSupportPreparedbySol-gel
;Method
;GUOHongx(郭红霞),(陈红萍),(梁英华),f芮玉兰),LU..ia
;(吕敬
;C
;德
;H
;)
;ENHongping
;(付占达
;L
;)
;IANGYinghuaRUIYulan
;JingdeandFUZhanda
;SchoolofChemicalEngineeringandBiologicalTechnology,HebeiPolytechnicUniversit
y,Tangshan063009,China
;1INTRoDUCTIoN
;PolycarbonaterPC)hasbeenrecognizedasat. ;tractiveengineeringthermoplastics,whichiswidely ;usedinindustriesassubstitutesformetalsandglass ;becauseofitsimpactstrength,heatresistanceand ;transparency.Thereisincreasingdemandforasafer ;andenvironmentallyfavorableprocessforPCproduc. ;tion.Thetransesterificationprocessusingdiphenols ;anddiphenylcarbonate(DPC)hasbeengivenmore ;andmorerecognitioninsteadoftheinterfacialpoly. ;condensationofdiphenolswithphosgeneduetothe ;advantagessuchasnotoxicphosgene,nosolventand ;nosaltformation【卜41.Phenolphosgenationmethod
;isgivenupbecausehighlytoxicsubstancesareused, ;whilethe缸ansesterificationmethodusingdimethyl ;carbonatefDMC)isnotadirectmethodfortheprepa. ;rationofDPC.Inrecentyears,adirectmethodof ;oxidativecarbonylationforDPCsynthesishasat. ;tractedkeenattentionasitinvolvesonlyasinglestep ;‘
;一
;reaction.
;Intheliterature,oxidativecarbonylationforDPC ;synthesisisbyhomogeneouscatalyticreactlonr5—71.
;Inthiscase,itisdifficulttoscale.uptheprocessdue ;toproblemsofproductseparationandcatalystrecov—
;ery.Asitsolvesmeproblemsposedbyhomogeneous ;catalyticsystem.theheterogeneouscatalyticroutefor ;DPCsynthesishasagoodpotentialtoproduceDPCin ;industryf8-20].1waneeta1.【21】usedPorouscarriers,
;suchascarbon,alumina,silicaandthelike,supported ;palladiumcatalyststopromotethesynthesisofDPC ;andtheyieldofDPCcouldreach12.6%.Takagieta1. ;【221reportedthat9.55%DPCyieldwasobtained ;whenusing5%rbymass)Pd/CascatalystandPbOas ;co—catalyst.
;Althloughtherewassomeachievementalready. ;theyieldofDPCwasstillrelativelylow.Inorderto ;improvetheyieldofDPCfurther,thesupportofthe ;catalystforthedirectsynthesisofdiphenylcarbonate ;(DPC,byheterogeneouscatalyticreacfionwaspre. ;paredbytheso1.gelmethod,andtheoptimumcondi. ;tionsforsynthesisofthesupportwerealsostudiedin ;thisworkbyo~hogonalexperiments.
;2EXPERIMEN1AL
;2.1Preparationofsupportbysol-gelmethod ;CufOAc)2?HEO,Mn(OAc)2?4H20,Co(OAc)2?4H20, ;citricacid.andethanediolwereusedasrawmaterials. ;CufOAc)2.HEO,Mn(OAc)2.4H20,Co(OAc)2.4HEO, ;citricacidweredissolvedwithdistilledwater,and ;theirconcentrationswere1.5,1.5,1.5,3.0mo1.L, ;respectively.Thestartingsolutionswerepreparedby ;mixingdifferentproportionofmetalacetatesolutions ;withl0mlcitricacidsolution,with2mlethanediolas ;additive.ThemolarproportionofCu,Mn,andCowas ;adjustedbychangingthevolumeofrespectivemetal ;acetatesolutionsandthetotalvolumeis30mlor40 ;m1.Theabovemixtureswerestirredforhoursinthe ;waterbathatpresettemperature,andthepHvaluewas ;adjustedto，10bydropwiseadditionofaquaalT1.
;monia.Thentheyweredriedundervacuumtogetthe ;precursors.Finallytheprecursorswerecalcinedatset ;temperaturefor6htogetblacknanometerpowderas ;thesupport,whosespecltlCsurIacearea,3’BET,wasin
;therangeof7.5—9.0mz’g.
;2.2Preparationofcatalysts
;Thecatalystswerepreparedbyimpregnation ;Received2007—06—29.accepted2007—11—26.
;Towhomcorrespondenceshouldbeaddressed.E—mail:Liangyh64@yahoo.corn.ca ;
;Chin.J.Chem.Eng.,Voi.16,No.2,April2008 ;method,whichusedactivatedcharcoal(purchased, ;madebvTaJ1gshanSuolideActivatedCarbonCo.), ;HZSM一5Omolecularsieve(purchased.byNankai ;University),porousceramics(purchased,byTangshan ;CeramicCo.),hopcalite(purchased,byShanxiXinhua ;ActivatedCarbonCo.),andthesupportpreparedby ;thesol—gelmethodascarrier,respectively.PdCl2was ;thekeYcatalyst,andCo(OAc),?4HEOwasthecocata—
;lyst.Atfirst,PdCl2andCo(OAc)2.4HEOweredis—
;solvedinabout25mlaquaammonia,andtheircon一
;一
;centrationsinsolutionwere0.034and0.24mol’L.
;respectively.Thesolutionwasdividedintofiveali—
;quots.Eachsupportwiththemassof1gwasdipped ;intoanaliquot,thenstirredfor1h,andagedfor13h, ;finallydriedundervacuumfor2hat55.C,andcal—
;cinedat6O0oCfor6h.
;2.3Characterizationofthecatalystandsupport ;2.3.1XRD
;X-raypowerdiffractionpatternswereobtainedat ;roomtemperatureusingBDX??3200withNi??filtered ;CuK?radiation.TheX—raytubewasoperatedat40
;kVand20mA.20anglewasscannedfrom10.to90.. ;2.3.2
;Theparticlediameterdistributionandaverage ;diameterofthecatalystweremeasuredbytransmis—
;sionelectronmicroscope(TEM)(JEM—IOOCXII).
;2.3.3Specificsurfacearea
;Thespecificsurfaceareasofallsampleswere ;determinedonaconstantvolumeadsorptionapparatus ;(GeminiV3365/2380)bytheN2BETmethodatliq—
;uidnitrogentemperature.
;2.4Oxidativecarbonylationofphenol
;SynthesisofDPCwascarriedoutina500ml ;high—pressureautoclave(madeinW_emai,China) ;equippedwithamagneticallydrivenimpeller,which ;waspre—filledwith50mldichloromethane.1gcata—
;lyst(Pdinthecatalyst=0.17mmo1),80mmolphenol,
;3mmolfC4H9)4NBr(tetrabutylammoniumbromide, ;TBAB),4mnaolhydrochinone,and2gof4A
;fl80-250~yn.60—8Omesh)molecularsieveusedas
;dryingagent.COandO2wererechargedintothere- ;actortothedesirepressure,andthereactionstarted. ;,enthereactionendedtheliquidproductwastaken ;out,weightedandanalyzedbygaschromatography(GC). ;2.5Orthogonalexperiments
;InordertoinvestigatetheeflfectOfdiflusionon ;selectivityandyieldofDPCbeforelookingforthe ;optimumconditionsofDPCsynthesis,thesynthesis ;OfDPCwascarriedoutunderdifferentratesofagita. ;tion,t}leresultsshowed.
;whentherotationratewas
;greaterthan600r.min1,theyieldandselectivityof ;DPCapproachedalmosttheasymptoticValues.Inad. ;dition,theaverageparticlediameterofthecatalyst ;wasonthenanometerscale,sotheeffectofdiflusion ;couldbeneglected.TheL9f3)orthogonaltablewas ;choseninthiswork,factorsandtheirlevelswerede—
;signedinTable1.
;Table1Factorsandlevelsoftheorthogonaiexperiment ;3RESUIrSANDDISCUSSION
;3.1Activityofdifferentcatalysts
;Table2showstheactivitiesofdifferentcatalysts. ;Theresultsindicatethatthecatalystusedthesupport ;preparedbythesol—gelmethodhashigheractivity.
;Table2Theactivityofdifferentcatalystsmadefrom ;varioussupports
;Note:r11Thereactionwascarriedoutunderthecondition: ;phenol80mmol,(C4Hg)4NBr3mmol,hydrochinone4mmol, ;catalyst1g,4Amolecularsieve2g,Pco/Po10,p5 ;MPa.T=l0ooC.f=6h.’
;f21Theselectivitywascalculatedbypeakareaforeachcom—
;ponentingaschromatograph.
;f31Theyieldwascalculatedbasedonpheno1. ;3.2Thecrystalphaseandaverageparticlediameter ;TheXRDpatternsofthesupportpreparedby
;sol—gelmethodareshowninFig.1.Thepatternsshow ;thepeakscorrespondingtocomplexoxidesCo2MnO4, ;Pd05Pd304,andSiO2,respectively.Inthepatternof ;thesupportbeforeloading,thereareonlystrongpeaks ;at3O.62..36-32.,44.O2.,58.6O.,4.33.intheirXRD ;patternsandthemalncrystalphaseisC02MnO4.So
;thecrystalphasemayhavemanycrystaldefects, ;whichspeedsupthecarbonylreaction.Afterloading, ;Figure1XRDpatternsofsupportpreparedbythesol?gel ;method(Cu:Mn:C01:1:1,calcination700.C,drying ;100.C,waterbath85.C)
;舟SiO2;OCo2MnO4;Pd0.
;5Pd304
;
;Chin.J.Chem.Eng.,Vo1.16,No.2,April2008 ;therearenotonlypeakscorrespondingtoCo2MnO4, ;butalsopeakscorrespondingtoPd05Pd3O4,forthe ;loadOfPdC1,.Afterreactiontheintensityofpeaks ;correspondingtoCo2MnO4andPd05Pd3O4decrease ;whilepeakscorrespondingtoSiO,appear,forthead—
;ditionof4Amolecularsieveasdesiccant,whosemain ;componentisSiO々.A1thoughCudoesnotenterthe
;crystalphase,italsocontributestotheactivityofcata- ;lystefficientlyaccordingtotheRefr2,6,14,23]. ;Inordertoinvestigatethedispersibilityandthe ;physicalstructure.theTEMpicturewiththesame ;supportinFig.1isshowninFig.2(a1.Theresults ;showthatthesupportdoesnothavegooddispersibil—
;ity,fornodispersantusedastherawmaterialswhen ;thesupportwaspreparedbythesol—ge1method,orthe
;relativelylowtemperatureofcalcination(500.C, ;600.Cor700.C,.Itsaverageparticlediameterisas ;lowas40nm.Correspondingelectrondiffractionpat—
;ternisalsoshowninFig.2(b1.Theresultscanbe ;seenthatthesupportformsthecrystalphase,which ;consistswiththeresultsofXRD.
;3.3Theresultsoforthogonalexperiments ;11ab1e3showstheresultsoftheninthorthogonal ;experimentalruns.WhenDPCsynthesisisunderthe ;conditionsoftheproportionof(Cu,Mn,andCo) ;1:1:1,temperatureofwaterbath80.C.temperature ;ofdrying800C,temperatureofcalcination700~C.bOth ;yieldandselectivityarehighestamong9experimental ;nJnS.
;11ofindouttheimportantfactorsinfluencingthe ;yieldandselectivityofDPC,theaNalysisofmaximum ;variancewasperformedandtheresultsareshownin ;11able4.
;IntermsoftheyieldofDPCfromTable4,the ;proportionofCu,Mn,andCoisthemostimportant
;factor.Thesecondimportantvariableisthetempera—
;tureofcalcination,thethirdistemperatureofdrying. ;(a)
;(b)
;Figu
;.
;re2TEMimagesandelectrondiffracffonpatternof ;earrlerDe10reloamng
;FromTable4itwasconcludedthatthebestconditions ;areproportion1:1:1,temperatureofwaterbath80.C. ;temperatureofdrying90.C.andtemperatureofcalci—
;nation700.C,
;IntermsoftheselectivityofDPC,theproportion ;ofCu,Mn,andCoisalsothemostimportant.The ;secondisthetemperatureofcalcination,andfollowed ;bytemperatureofwaterbathandtemperatureofdry—
;ing.Theoptimumconditionsare:proportion1:1:1. ;Table3Conditionsandresultsoftheorthogonalexperiment ;Table4Marginsofyieidandselectivity,Rl,andRx,forDPC(%) ;
;Chin.J.Chem.Eng.,Vo1.16,No.2,April2008 ;temperatureofwaterbath85oC.temperatureofdrying ;90~C,andtemperatureofcalcination7OooC. ;Althoughtheoptimumconditionsweretestedby ;theorthogonalexperimentabove,manyfactorssuch ;astemperaturesofwaterbath,drying,andcalcination ;wereattheborderoforthogonalexperiments,sothe ;secondorthogonalexperimentwasconducted. ;Basedontheresultsabove,theproportionofCu, ;Mn,andCocouldbefixedto1:1:1,butthetem. ;peraturesofwaterbath,drying,andcalcinationneed ;tObetestedfurther.Inordertogettheiroptimumfac. ;tors,theL9(3)orthogonaltablewaschosenandthe9 ;experimentalrunswereconducted(Table51.There ;wereonlythreefactors,soanemptycolumnwas ;added.Theresultsareshownin]r2le6.
;Table5Factorsandlevelofthe2ndorthogonalexperiment ;Fromle6.itisclearthatwhenthereaction
;takesplacewithtemperatureofwaterbam85.C.tem. ;peratureofdrying1OooC.temperatureofcalcination ;700~C,theyieldandselectivityarethebest. ;Table7showstheresultsofmarginanalysisin ;thesecondexperimentalset.Itrevealsthatregarding ;theyieldOfDPC.temperatureofcalcinationisthe
;firstimportantfactor.Thesecondistemperatureof ;waterbath,followedbytemperatureofdrying.Ac. ;cordingtoTable7,thebestreactionconditionsshould ;betemperatureofcalcination700~C,temperatureof ;drying100.C.temperatureofwaterbath85oC. ;AsfortheselectivityOfDPC.temperatureofca1. ;cinationisalsothefirsteffectivefactor,followedby ;temperatureofwaterbath,andtemperatureofdrying. ;Thebestreactionconditionsshouldbetemperatureof ;calcination7OooC,temperatureofdrying110~C.tem, ;peratureofwaterbath85.C.
;Inordertoacknowledgethesignificanceofthe ;factorsofthe2ndorthogonalexperimentfurther,the ;varianceofyieldwasanalysed(Table8,.Theresults ;showthattemperatureofcalcinationishighlvobvious ;(),andtemperatureofwaterbat}lissignificant(), ;whichcorrespondswiththemarginanalysisfle71. ;Thevarianceanalysisofselectivityissimilartovari. ;anceanalysisofyield,soitisnotnecessarytointro—
;duceagain.
;Table8Thevarianceofyield,SrforDPC
;Ontheonehand,itcanbeseenfromtheexperi
;mentsthattheproportionOfCu.Mn.andCoplaysan ;importantroletotheyieldandselectivity,Itshows ;thatmoreandmorecocatalystsarenotfavorableto ;thereaction.Ithasanoptimalvalue,underwhichthe ;effectOfsynergismisthebest.Thereasonthatthe ;temperatureofcalcinationisthesecondimportant ;factorshouldbethatitiscloselyrelatedtothesurface ;areaofthesupport,whichisvitaltotheactivityofthe ;catalyst.Ontheotherhand,itcanbeconcludedthat ;coppercobaltmanganesemixedoxidesusedasthe ;supportanditspreparationbytheso1.gelmethodare ;allresponsiblefortheenhancementofthecatalytic ;Table6Conditionsandresultsoftheorthogonalexperiment ;Table7Marginsofyieldandselectivity,RrandRxforDPC ;,%y,%,%R,%Srx104x:,%x,%/%
;274
;247
;225
;222
;,%
;59
;9
;68
;38
;Sxxl0
;435.125
;10.125
;578
;180.5
;temperatureofwaterbath
;temperatureofdrying
;temperatureofcalcination
;emptycolumn ;2l
;28
;84
;4l
;39
;49
;24
;44
;66
;49
;l8
;4l
;45
;2l
;66
;3
;253.125
;55.125
;544.5
;1.125
;2l5
;238
;286
;260
;24o
;244
;2l8
;247
;
;Chin.J.Chem.Eng.,Vo1.16,No.2,April2008227
;activityaccordingtomeRef.[23],butmechoiceof
;coppercobaltmanganesemixedoxideswithproper6
;compositionismoreimportant.
;4CONCLUSIoNS
;f1,Theactivityofmecatalystbasedonthesup—
;portpreparedbythesol—gelmethodishighermanme ;othertestedcatalysts.
;f2,Theorthogonalexperimentshowsthatthe ;proportionofCu.MnandCoismefirstimportant ;factorinfluencingmeyieldandselectivitytoDPCand ;thetemperatureofcalcinationisthesecondone. ;f3,Theoptimumreactionconditionsshouldbe ;proportionofCu,Mn,andCo1:1:1,temperatureof ;calcination700~C.temperatureofdrying100.C,tem—
;peratureofwaterbath85.C.
;f4,TheyieldandselectivityofDPCinmeproc—
;esscanreach38%and99%.respectively. ;(5)Choosingcoppercobaltmanganesemixed ;oxidesasthesupportisanimportantfactoronthe ;highercatalyticactivitymanthatbasedonthesupport ;preparedbymesol—gelmemod.
;NoMENCLATURE
;statisticalparameter
;degreeoffreedom
;reactionpressure,MPa
;maximumvarianceofXamongfactors.% ;maximumvarianceofYamongfactors.% ;varianceofXforeachfactor
;varianceofYforeachfactor
;reactiontemperature,.C
;reactiontime,h
;selectivityofDPC.%
;yieldofDPCbasedonpheno1.%
;scanningangleofXRD,(.)
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;2
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