硅溶胶胶凝过程的分形特征

:20091022:(2010CB732301):,Tel:[phone];Email:[e-mail]:10018719(2010)06084105杨丽静1,田辉平1,龙军1,李志宏2(1.,100083;2.,100039):,pHXpH,Porod,1,2,,:;;X:TQ039:Adoi:10.3969/j.issn.10018719.2010.06.002FRACTALOFSILICASOLDURINGSOLGELPROCESSYANGLijing1,TIANHuiping1,LONGJun1,LIZhihong2(1.ResearchInstituteofPetroleumProcessing,SINOPEC,Beijing100083,China;2.BeijingSynchrotronRadiationLaboratory,InstituteofHighEnergyPhysics,ChineseAcademyofSciences,Beijing100039,China)Abstract:FCCcatalystswithsilicasolbindercanenhancetheselectivitytogasolineandreducecokeyieldinFCC,yettheunstabilityofsilicasolsisabottleneckofitsutilization,whichmaybecausedbythepHvalueofsilicasolitself.SmallangleXrayscattering(SAXS)techniquewithsynchrotronradiationwasusedtostudyfractalstructuresofsilicasolswithdifferentpHvalue.TheresultsindicatedthatboththeacidicandalkalinesilicasolspresentednegativedeviationfromPorodslaw.Onlyonekindofsurfacefractalcouldbefoundintheacidicsilicasolandtheaggregationprocessbelongedtoreactionlimitedcolloidalaggregation(RLCA).Whereas,inthebeginning,twokindsofsurfacefractalcouldbeseeninthealkalinesilicasolandoneofthemevolvedtoeitherporefractalormassfractalbeforegelationwiththeotherremainedsurfacefractal.Keywords:silicasol;fractal;smallangleXrayscattering,,,VGO,,FCC(),,[1],()201012ACTAPETROLEISINICA(PETROLEUMPROCESSINGSECTION)266pH,,,,,,X(SAXS),,1SAXSX,X(23),2,X(SAXS)[2-3]SAXSq,q=4sin/,2,XI(q),2030,SAXS,SAXS,,[4-9]1973,[10-11],,,,(),,,(Fractaldimension)[12],(Surfacefractal,)(Massfractal,)(Porefractal)[2,13]Ds,,2!Ds!3,Ds,Dm,,0!Dm!3,Dm,Dm=3(),Dm3()Dp,,0!Dp!3,Dp,Dp=3(),Dp322.1,,Na2O9.24%,SiO228.80%,(98%),,,pH7.0,2.2,,pH3.1SiO28.0%,,10150300380500520560min,8a18a28a38a48a58a68a7560min,,pH10.8SiO28.0%,,15180320430520540min,8b18b28b38b48b58b6540min2.3SAXS(BSRF)4B9AX22.2GeV,60mA,,X0.138nm,842()263SAXS12,XRD121SAXSTable1SAXSresultsofacidicsilicasolsamplesSamplePoroddeviationFractalnatureFractaldimension8a1NegativeSurface2.098a2NegativeSurface2.258a3NegativeSurface2.368a4NegativeSurface2.398a5NegativeSurface2.288a6NegativeSurface2.228a7NegativeSurface2.172SAXSTable2SAXSresultsofalkalinesilicasolsamplesSamplePoroddeviationFractalnatureFractaldimension(Highangle/lowangle)8b1NegativeSurface/Surface2.41/2.248b2NegativeSurface/Surface2.60/2.278b3NegativeSurface/Surface2.90/2.288b4NegativeSurface/Surface2.89/2.198b5NegativeMassorpore/Surface2.70/2.188b6NegativeMassorpore/Surface2.92/2.161XRDFig.1XRDpatternsofacidicsilicasolsamples(1)8a1;(2)8a2;(3)8a3;(4)8a4;(5)8a5;(6)8a6;(7)8a72XRDFig.2XRDpatternsofalkalinesilicasolsamples(1)8b1;(2)8b2;(3)8b3;(4)8b4;(5)8b5;(6)8b612,,,Porod,,,2.092.39,2.172,,12,pHSiO2,I(q)q,34,343lnI(q)lnqFig.3lnI(q)lnqcurvesforacidicsilicasolsamples(1)8a1;(2)8a2;(3)8a3;(4)8a4;(5)8a5;(6)8a6;(7)8a784364lnI(q)lnqFig.4lnI(q)lnqcurvesforalkalinesilicasolsamples(1)8b1;(2)8b2;(3)8b3;(4)8b4;(5)8b5;(6)8b6lnI(q)lnq,,,,,,;,,[14]34,,lnI(q)lnq,,,3lnI(q)lnq1,4lnI(q)lnq21,2,[15],1,()(DLCARLCA),D=1.7,;D=2.08,[16],2.08,RLCA,22.12~2.28,,,,Wittensander,Eden,[17],SiOHSiO-Si∀O∀SiSi∀O∀Si90150,,,[18],,,Si∀OHSi∀O-,,,,,,,,[19],,pH(8.5)[20],4(1),,Porod,(2)1,2,,844()26(3),[1].[J].,1998,28(6):3637.(LIQiaoling.EffectsofpHvalueonthestabilityofsilicasol[J].HunanChemicalIndustry,1998,28(6):3637.)[2].SAXS[D].:,2002.[3].X∀∀∀[M].:,2008.[4],,.X[M].:,1989.[5].X[M].:,1966.[6]DEBYEA,ANDERSONHR,BRUMBERGERH.Scatteringbyaninhomogeneoussolid#Thecorrelationfunctionanditsapplication[J].JApplPhys,1957,28:679683.[7]DEBYEA,BUECHEAM.Scatteringbyaninhomogeneoussolid[J].JApplPhys,1949,20,518526.[8]PORODG,KRATKYO.DiffusesmallanglescatteringofXraysincolloidsystems[J].JColloidSci,1949,4(1):3570.[9].X[J].,2006,12(6):1114.(XUPeicang.ThestudyofsmallangleXrayscatteringformolecularnetworkfractaldimensioninlowdimensionsilicates[J].JournalofJiangsuTeachersUniversityofTechnology,2006,12(6):1114.)[10].[M].:,2004.[11],.[M].:,1997.[12].[J].,2003,24(11):20512055.(ZHAOZhenguo.Surfacefractalanalysisofsilicagelbyusingadsorptiondata[J].ChemJChineseUniversities,2003,24(11):20512055.)[13],,.[J].,2004,27(1):1417.(LIZhihong,GONGYanjun,WUDong.Fractalofmesoporoussilica[J].NuclearTechniques,2004,27(1):1417.)[14]GLATTERO,KRATKYO.SmallAngleXrayScattering[M].NewYork:AcademicPress,1982.[15]THOMASDN,FAWCEETN.Flocculationmodeling:Areview[J].WatRes,1999,33(7):15791592.[16]KNOBLICHB,GERBERTH.AggregationinSiO2solsfromsodiumsilicatesolutions[J].JournalofNoncrystallineSolids,2001,283:109113.[17],,,.∀∀∀XX[J].,1987,3(3):106109.(MAOYan,WANGGuoxiong,CHENRongsan,etal.StudiesonsilicicacidanditssaltsXX∀∀∀relationshipbetweenacidstrengthandmolecularstructuresofpolysilicicacidinsolution[J].JournalofInorganicChemistry,1987,3(3):106109.)[18]VANSANTENRA,BEELENTPM,VANGARDERENHF,etal.Aggregationandaginginsilicagel[J].NuclInstrandMethinPhysResB,1995,97:231237.[19]LECHGMACHOWSKI.Aggregaterestructuringanditseffectontheaggregatesizedistribution[J].ColloidsandSurfacesA:PhysicochemEngAspects,2002,207(276):27127.[20]ILERRK.TheChemistryofSilica[M].NewYork:Wiley,1979.:,,,;,,,,;,,,,;,,,,8456