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scale Self-assembly Technique

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scale Self-assembly Technique

    scale Self-assembly Technique

    ChinaPetroleumProcessin~andPetrochemicalTechnolo~v

    2010Vo].12,No.1,pp13-16

    PreparationandCharacterizationofA1203--TiO2Complex

    SupportsbyNano--scaleSelf-assemblyTechnique

    LiKuanbiao;LiPing;WangDingcong;ZhaoShanlin

    f.LiaoningUniversityofPetroleumandPetrochemicalTechnology,Fushun113001 2.FushunResearchInstituteofPetroleumandPetrochemicals)

    Abstract:Thetwo..stepnano..scaleself-assemblytechniqueandtheframeworkstructuremechanismforforming

    mesoporoussupportswereemployedforpreparingA1203

    TiO2complexsuppo~swithlargeporevolumethat

    wereappliedformanufacturingtheresidhydrotreatingcatalysts.TheinfluenceofdifferentTiO2contentsand

    calcinationtemperaturesonspecificsurfacearea,porevolumeandporesizedistributionofcomplexsupportswas

    studied.TEMandSEMwereemployedtocharacterizetheA1203

    TiO2complexsupports.Testresultsrevealedthat

    thespecificsurfaceareaofAI203

    TiO2complexsupportswasthelargestataTiO2massfractionof20%,andwhen thecalcinationtemperaturewasintherangebetween300?

    to700?.theporedistributionofthecomplex

    supportwasstable.CharacterizationofthecomplexsupportbyTEMandSEMdemonstratedthatTiO2washomo

    geneouslydistributedinthecomplexsupport,whichwasinfavorofcarryingactivecomponents.TheA1203TiO2

    complexsupportscanfunctionasthebestcatalystsupportforresidhydrotreatingcatalysts.

Keywords:nanoself-assembly;alumina;titaniumdioxide;complexsupport;porestructure

    TheAI203.TiO2complexmaterialisanexcellentcata- lystsupportthathasthecatalyticpropertyofbothA1203 andTiO2andcanmakeupforthedisadvantagesofsmall specificsurfaceareaandlowmechanicalstrengthchar? acteristicofTiO2,whileretainingtheabilityofTiO2in termsofitsanti--cokingandpoisoning--resistant performance.CombinationofA12O3withTiO2canresult inauniquephysico-chemicalpropertythatcannotbe possessedbyanyoneofthesetwooxides.Currentlythe A12O3TiO2complexsupportisbeingextensivelyap

    P1iedinsuchcatalyticreactionsasresiduum hydr0desulphurizationandhydrodenitrogenationreac

    tionstopromisegoodprospectsforcommercialappli

    cations[.However,thesupportfortheresid

    hydrotreatingcatalystsisgenerallymadeofmacroporous aluminaanditsmodifiedproducts.Thecommonmeth

    odsformanufactureofmacroporousaluminaincludethe physicalporecreationmethodthehightemperature

    calcinationmethod[.andthepHswingmethod4_The

    disadvantageofphysicalporecreationmethodisthe nonhomogeneityofchannels,whilethepHswing methodcanobtainmacroporousaluminawithporedi

    ametersintherangeof1020nm.whichwouldcon

    tractsignificantlyintosmallerporesinthecourseof peptizationinacidicpeptizingmedium.Thehightern-

    l3

    peraturecalcinationmethodhasthedisadvantageoflos

    ingacidityandlimitedabilityforexpandingpore diameter.Althoughinorganicpolymerizationreactions

    usinghighmolecularcolloidalcrystallitest]and microemulsions~asthetemplatecanalsoformordered macroporousmaterials,itisimpossibletomanufacture aluminasupportcharacteristicoflargeporevolume, highstrengthandhighspecificsurfaceareaduringthe materia1formingprocess.

    Theonestepnano.sizedaluminumhydroxidewassyn. thesizedin-situviasupersolubilizingself-assembly nanotechnique,andthenano-scalealuminumhydrox- ideincombinationwithasurfactanthavingaVBvalue oflessthan1wastransformedintoasphericalorrod

    liketwo?-stepself-assemblednano??aluminumhydroxide materia1.Thetwo-stepself-assemblednano-sizedalu

    minumhydroxidematerialwasherebyusedasthetern- platetomanufacturealuminasupportsthathadapore volumeof1.82.7cm./g.aspecificsurfaceareaof

    180430m/g.aporosityof88%93%andanaver-

    ageporediameterof1757nm.whichweresuitedfor

    preparingtheresidhydrotreatingcatalyst7J.Theauthors

    basedonthepreviousworkhavepreparedthetwostep

    self-assemblednano--sizedA1203?TiO2complexsuppo~

    Correspondingauthor:Mr.LiKuanbiao.Email

    likuanbiao@163.com

    LiKuanbiao.eta1.PreparationandCharacterizationofA120~-Ti02ComplexSuppo~sbyN

    anoscale

    Self-assemblyTechnique

    byincorporatingadefiniteamountofTiO2asanano

    additive.TheinfluenceofTiO2dosageandcalcination temperatureonspecificsurfacearea,porevolume,and porediameterofcomplexsupportswasinvestigated,

alongwithcharacterizationbyTEMandSEM.Charac

    terizationresultshadrevealedthatcomplexsupports preparedbytheabove??mentionedtechnologyhadex-

    cellentperformancetobeusedasthesupportforresid hydrotreatingcatalysts.

    2Experimental

    2.1Feedstocks

    Triethanolaminepolyisobutynemaleatewassynthesized inourlaboratory;150SNbaseOwasacommercially

    availableproduct;Deionizedwaterwaspreparedinour laboratory;AI(NOa)3'9H20,urea,TiO2,aceticacid,and ethanolwereanalyticallypurereagents.

    2.2Analyticalinstruments

    AJapaneseJSM--6301Ftypescanningelectronmicro.- scopewithanacceleratingvoltageof20kVwasusedto examinethemorphologyandsizeofselgassembled nanoparticles.Atransmissionelectronmicroscope (typeTECNA120,madeinHolland),withamagnifica

    tionofl,000,000wasusedtoinspecttheappearance, dispersion,sizeanddistributionofself-assemblednano

    particles.AnAUTOPOREII9220typemercury

    porosimeterandaMicromeritics'acceleratedsurface area&porosimetryinstrumentfASAP2405)wereused bymeansofmercuryandphysicaladsorptiontoana

    semblednanosizedsupersolublizingmicellaewere obtained.Theonestepsupersolublizingmicellaewith differenttemplatecontentscouldbegenerateddepend

    ingupondifferentmassratiosbetweenoilphaseand eutecticmassinordertoregulatetheporedistribution

ofthesample.Forthetwosteppreparationofself-as

    semblednanoA1203supportthemassratiobetweenthe oilphaseandtheeutecticmasswas12:88.Adefinite amountofsuperso1ublizingmicellaewasplacedinthe autoclaveandwassubjectedtoreactionsatacertaintem

    peraturefor1l0hours.andthereactionproductswere washed35timeswithdeionizedwaterpriortobeing centrifugedatarotatingspeedof2000--5000r/min.In thecourseofwashingadefiniteamountofnano.addi-

    tiveTiO2wasincorporated.Theprecipitateobtained duringcentrifugationwasbakedat80120.Cand therebythetwostepself-assemblednanosizedAI!O3

    TiO2complexsupportwasobtained.

    Thetwostepself-assemblednanoscaleAI2O3I'iOcom

    plexsupportwascrushedandscreened,andparticles largerthan100meshwasseparatedforspecialuse.The powderedcomplexsupportwasmixedwithadefinite ratioofadhesive(activatedalumina)alongwithaddi

    tionofabindingagent,thedeionizedwater,apeptizing acid(aceticacid)andasolvent(ethano1).Theabove mentionedmaterialswerethoroughlymixedandformed throughextrusion.Theextrudatewascalcinedina mufnefumaceatdifferenttemperaturestoyieldthetwo

    stepself-assemblednanoscaleAI2O3TiO2complexsup

    portsampleswithlargeporevolume.

    1yzetheporevolume,porediameterandspecificsu3R

    esu1tsandDiscussi0n

    facearea(byBET)oftheparticlesamples.

    2.3Preparationoftwo-stepAl0-TiOcomplexsupport Vianano-self-assembledtechnique

    ThereagentAI(NO3)39H20wasmixedunderstirring withureaatadefinitemassratio,andthemixturewas heatedto100.Cuntilaeutecticmasswasformed.The surfactanttriethanolaminepolyisobutynemaleatewas mixedunderstirringwiththe150SNbaseoilatadeft

    nitemassratioandwasheatedtol00?untilahomo.

    geneousoilpilasewasformed.Theoilphasethusob

    tainedwaspouredintothestirrerintowhichtheeutec

    ticmasswasaddedundervigorousstirringtoform supersolubJizjngmicellae.Herebytheonestepself-as

    14

    3.1Influenceofcalcinationtempel'atm.eonspecific surfaceareaandporestructureofA10TiOcomplex

    support

    Thetwostepself-assemblednanoscaleA12O3TiO2com

    plexsupportcontaining20%TiO2(usedasanano

    additive)wasputinamufflefurnaceandwascalcined attemperaturesrangingfrom300?to700?.andits

    specificsurfacearea,porevolume,porediameterand poredistributionweremeasuredbytheBETmethod. withthetestresultspresentedinTable1. ItcanbeseenfromTable

    tiontemperatureledtoa

    1thatincreasingthecalcina

    decreaseinthespecificsur

    Table1Poredistributionof~vostepsel~assemblednanoscale AI2O3TiO2complexsupportcalcinedatdifferenttemperatures Calcinationtemperature~C

    Itemsj3005oo70O

SpecificsurfaCearea,m./g3,s.5307.252.l

    Porevolume,mL/g06930.7170804

    Averageporediameter,nm|8.799.34

    I

    :ii1276

    Poredistribution.%

    耀<l0nm49.,447iit

    lO30tim36.361187

    3Q_60tim972

    4_3

    4z103

    >60rim4.314199

    faceareaoftwostepself-assemblednanoscaleA1203

    TiO2complexsupport,whereasitsporevolumeandav

    erageporediametergraduallyincreased,whichwasat

    tributedtoagglomerationofTiO2at700.C.Meanwhile, withanincreasingcalcinationtemperature,theratioof microporesgraduallydecreasedandtheratioof macroporesgraduallyincreased.However,inatempera

    turerangebetween300.Cand700.Cninetyfiveper

    centofporesinthecomplexsupportweremainlyless than30nm,sothattheporedistributionwasrelatively stable.Allthesedataindicatedthatthetwostepself-

    assemblednanoscaleA1203TiOecomplexsupporthad

    excellentspecificsurfaceareaandporestructure,which couldpromotetheloadingofactivecomponentsonto thesupporttoapparentlyenhancetheoverallactivity ofthecatalyst.

    3.2Influence0fdifferentcontentsofnano.additiveTio

OHphysicalpropertyofthetwostepself-assembled

    nanoscaleAIO-TiOcomplexsupport

    ThecatalystwithA1203TiO2complexsupportduringthe selectivehydrogenationreactionsdemon

    stratedthatithadbetterlowtemperature

    activity,higherselectivityandgoodpoison

    ing?-resistantabilityascomparedtothecata?- lystcomprisingasingleA1203support,while concurrentlymakingupforthedisadvan

    tagesofsmallspecificsurfaceareaandlow mechanicalstrengthofTiO2,andcouldfunc

    tionasgoodcatalystsupport.

    SincethephysicochemicalpropertiesofCO1TI

    plexsupportarethemajortactm'saffecting thecatalyticperformanceoftherelevantcatalyst,thereby

    thechemicalcompositionofcomplexsupportwould directlyaffectitsphysicochemicalproperties.Itwasrec

    ognizedthatatacalcinationtemperatureequatingto300 ?itwouldbeimpossibletocompletelyburnoffthe carbonelementcontainedinthesupport.andat700?

    agglomerationofTiO2couldtakeplace,sothecalcina

    tiontemperaturewasspecifiedat500.Cwhereinthetwo

    stepself-assemblednanoscaleA1203?-TiO2complexsup-- portsamplescontaining0%,15%,20%,50%,and100% nanoadditiveTiO2,respectively,werepreparedand 1abeledasFA1(0%)(j.e.thetwostepself-assembled

    nanoscaleY-A1203with0%TiO2),FA2(containing

    15%Ti02),FA3(containing20%TiO2),FA4

    (containing25%TiO2),FA5(containing50%TiO2)and

    FA6(consistingofexclusively100%TiO2support), respectively.Thesixsupportsampleswerecharacter

    izedbyBETmethodinordertoinvestigatetheeffectof TiO2contentonphysicalpropertiesofthetwostepself-

    assemblednanoscaleA1203TiO2complexsupport.The

    physicalpropertiesofthecomplexsupportsampleslnea

    sHredbyBETmethodarepresentediflTable2. ItcanbeseenfrO1TIdatalistedinTable2thatthe cificsurfaceareaofthecomplexsupportwasgr spe

    eater

    thanthatofeitherYA1203support(FA1)orTiO2sup

    port(FA6).WhentheTiO2contentinthecomplexsup

    portwaslessthan20%,thespecificsurfaceareaofthe complexsupportincreasedwithanincreasingcontent ofTiO2.WhenTiO2contentinthecomplexsupportwas greaterthan20%,thespecificsurfaceareaofthecorn

    plexsupportdecreasedmarkedlywithanincreasing contentofWiO2,whichwasmainlycausedbytherela

    tivesmal1specificsurfaceareaofTiO,sincethespe

    Table2InfluenceofdifferentcontentsofnanoadditixeTiO2on physicalpropertiesofthetwostepself-assemblednanoscale Ai203TiOzcomplexsupport

    Specifics~faceorevolu~e,Ay~ragep0reAvOfageparticle San1plejarea,'i:cm3|jdiameter,diameter,tim

    FR;i173~;28.966|j

    ;:241.314;5207

    FA..

    1323"9.511i|~i!iii!

    Fa42|7|42225i|

FAI515413o32i:.8.2.90,|

    FA.68.6250.29.1400J

    l5

    LiKuanbiao?eta1.PreparationandCharacterizationofAIeO3

    TiO2ComplexSuppo~sbyNanoscale

    Self-assemblyTechniGue

    cificsurfaceareaofpureTiO2wasonly8.625m/g. Furthermore,theaverageparticlediameterof1,A12O3

    supportandTiO2supportwas17.4nmand10.01nm. respectively,whiletheaverageparticlediameteroftwo

    stepself-assemblednanoscaleA1203--TiO2complexsup-- portwassmallerthan10nm.

    3.3Morphologyoftwo-stepself-assemblednanoscale Al0TiOcomplexsupport

    Figure1showstheTEMandSEMphotographsoftwo

    stepself-assemblednanoscaleA1203--TiO2complexsup-- portcontaining20%nanoadditiveWiO2.Thecomplex

    supportwasmadefromamixtureofoilphaseandeu

    tecticmassataratioofl2:88andwascalcinedat500?

    toyieldthesaidcomplexsupportwithaspecificsur

    faceareaof307.2m/g.aporevolumeof0.717cm/g. anaverageporediameterof9.34nm.andanaverage particlediameterof7.51nm.ItcanbeseenfromFigure 1thatthesphericalparticulatesofTiO2werehomoge

    neouslydistributedinthetwo-stepself-assembled nanoscaleA1203TiO2complexsupportwithexcellent dispersibilitythatcouldfavortheloadingofactive components.

    4Conclusions

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