GBT-19587-2004-气体吸附BET法测定固态物质比表面积-英文

GB/T19587-2004PrefaceThisstandardisnotequivalenttoadoptISO9277:1995“DeterminationofthespecificsurfaceareaofsolidsbygasadsorptionusingtheBETmethod”.Theadded,subtractedandmodifiedcontentsofthisstandardtoISO9277:1995asbelow:Theaddedcontents:-----Thescopeoftestcoversnanometerpowder;-----Add6termsin3.1section,including“equilibriumadsorptionpressure””saturationvaporpressure””relativepressure””adsorptionamount””molecularcross-sectionalarea””monolayeramount”;-----Addtheauxiliaryequipmentsin5.2section,including“balance””Dewarflask””samplevessel””vaporpressurethermometer”;-----Addtheconversionformulabetweengranularityandspecificsurfaceareain8.5section;Thesubtractedcontents:-----CancelthecontrolequipmentsinGraph1,3,4,andtheadsorptionisotherminGraph5,6;-----CanceltheappendixAandB;Themodifiedcontents:-----Specificmentionthefactorofdeadspaceinvolumetricmethod,therelativepressureinchromatographyandthecalculationformulaofadsorptionamountforthreemeasurementmethods,buttheISOstandardjustsaid”applyingthegeneralgasstateequationtoconfirm”.GB/T19587-2004DeterminationofthespecificsurfaceareaofsolidsbygasadsorptionusingtheBETmethod1.SCOPEThisstandardstipulatesthedeterminationmethodofspecificsurfaceofsolidsbygasadsorptionBETprinciple.Thisstandardissuitabletotestthespecificsurfaceareaofpowderorporousmaterial(includingnanometerpowderandnanometergradeporousmaterial)。Thetestscopeis0.0001m2/g～1000m2/g.2.NORMATIVEREFERENCEGB/T5314themethodofsamplingforpowderinmetallurgy3.TERMSANDSYMBOL3.1TERMS3.1.1AdsorptionTheadsorptiongasgatheringonthesolidssurface3.1.2PhysisorptionAdsorbateandadsorbentiscombinedtogetherwiththeweakbond.Ifslightlychangethepressureortemperature,theprocesswillbereversed.3.1.3AdsorptivegasTheadsorbedmeasurementgas3.1.4AdsorbentThesolidsforadsorbingthemeasurementgas3.1.5AdsorbateThegatheringadsorptivegasonthesurfaceofadsorbent3.1.6EquilibriumadsorptionpressureThegaspressureastheequilibriumwiththeadsorbate3.1.7SaturationvaporpressureGB/T19587-2004Thevaporpressureofcompleteliquidationadsorbateundertheadsorptiontemperature3.1.8RelativepressureTheratioofequilibriumadsorptionpressuretosaturationvaporpressure3.1.9AdsorptionamountUndertheequilibriumadsorptionpressure,theamountofadsorbedgasbyadsorbent3.1.10AdsorptionisothermUndertheconstanttemperature,thecurvegainedfromdrawingofadsorptiongasamounttoequilibriumpressureorrelativepressure.3.1.11Molecularcross-sectionalareaWhenthecompletemonolayeradsorption,theoccupiedareaofadsorptivemolecule3.1.12MonolayeramountTheamountofadsorbateofformingmonolayerontheadsorbentsurface3.1.13SpecificsurfaceareaThesolidssurfaceareaofunitweightorunitvolume3.2SYMBOLThesymbolofthisstandardasTable1Table1SYMBOLINTRODUCTIONUNITAtheslopeofBETchartcm-3Adareaofdesorptionpeakcm2Asareaofstandardpeakcm2BtheinterceptofBETchartcm-3CtheconstantofBETdavetheaverageparticlesizeofpowdernmmtheweightofsamplegm1theweightofsamplebottleonthevacuumstategm2theweightofsamplebottleundertheequilibriumpressuregGB/T19587-2004SYMBOLINTRODUCTIONUNITm3theweightofsampleandsamplebottleonthevacuumstategm4theweightofsampleandsamplebottleundertheequilibriumpressuregNtheAvogadroconstant,6.022X1023PtheequilibriumadsorptionpressurePaPAtheatmospherepressurePaPcthepressureofheliumfilledintotheburetPaPc’thepressureintheburetafterheliuminflatingtothesamplebubblePaPethepressureofadsorbategasfilledintotheburetPaPothesaturationvaporpressurePaP/PotherelativepressureRHecarriergasflow(e.g.helium)mL/minRXtheadsorbategasflowmL/minRrthetotalflowofmixturegasmL/minSthetotalsurfaceareacm2SVthevolumespecificsurfaceaream2/cm3SWtheweightspecificsurfaceaream2/gttheenvironmenttemperatureoftest℃Vtheadsorptionvolume(standardstate)cm3Vetheadsorptiongasvolumefilledintotheburet(standardstate)cm3Vpthevolumeofburetcm3Vmtheadsorptionvolumeofmonolayercm3Vrtheresidueadsorbategasvolumeinburetandsamplebubbleafterreachingtheequilibriumcm3Vsthefilledadsorbategasvolumeinvolumetube(standardstate)cm3Vtthevolumeofstandardvolumetubecm3Vothevolumeof1moladsorbate(standardstate),22.414cm3ρeffectivedensityofsamplematerialg/cm3ρodensityofgas(standardstate)g/cm3σthecross-sectionalareaofadsorbatemolecularcm2øthecorrectionfactorofdeadspacecm3/PaVm.mpmonolayeradsorptionvolumefrommultipointmeasurementcm3Vm.spmonolayeradsorptionvolumefromsinglepointmeasurementcm34.PRINCIPLEThesampleputintothegassystem,thephysisorptionwillhappenonitsmaterialsurface(thesurfaceareaofgranuleoutsideandinnerthrough-pore,asshowninfigure1)atlowtemperature.Whentheadsorptionreachingtheequilibrium,measureequilibriumadsorptionGB/T19587-2004pressureandadsorptiongasamount,aspertheBETequation(1)tocalculatetheadsorptionamountofsamplemonolayermolecularFigure1withdashlineindicatingthemeasuredgranulesurfaceareabyadsorptionmethodP/PVP/PCVC X P/Po VC …………（1）MakeP/PoasX,P/PVP/PasY,CVCasA,VCasB,thengainastraightequationY=AX+B,withslopAandinterceptB,drawingasshowninfigure2.Figure2BETchartFigure2isnormallylinearwhentherelativepressureisintherangeof0.05～0.30,butthetwoendpointssometimeswilldeviate,ignoretheway-offpointswhilecalculation.T