Designation:D3908−03(Reapproved2015)StandardTestMethodforHydrogenChemisorptiononSupportedPlatinumCatalystsbyVolumetricVacuumMethod1ThisstandardisissuedunderthefixeddesignationD3908;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthedeterminationofthechemisorptionofhydrogenat298K(25°C)onsupportedplatinumcatalyststhathavebeenreducedinflowinghydrogenat723K(450°C).Itincorporatesastaticvolumetricvacuumtechniqueatconstantvolume.1.2Thetestmethodisintendedforuseonunusedsupportedplatinumonaluminacatalystsofloadingsgreaterthan0.3weight%.Dataonothersupportsandlowerplatinumloadingswerenottested.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D3766TerminologyRelatingtoCatalystsandCatalysisE177PracticeforUseoftheTermsPrecisionandBiasinASTMTestMethodsE456TerminologyRelatingtoQualityandStatisticsE691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethod3.Terminology3.1Definitions—SeeTerminologyD3766.3.2QualityandStatistics—SeeTerminologyE456.3.3PrecisionandBias—SeePracticeE177.3.4Symbols—Thefollowingsymbolsareused:Pc=pressureofgasincalibratedbulb,torrPmc=pressureofgasincalibratedbulbandmanifold,torrPm=pressureinmanifold,torrPmd=pressureinmanifoldanddeadspace,torrPmx=pressureinmanifoldpriortoexpansionintosampletubeforXequilibrationpoint,torrPex=equilibriumpressureafterexpansionforgen-eratingXequilibriumpoint,torrVc=volumeofcalibratedbulb,cm3Vm=volumeofmanifoldbetweenstopcocks12and2withonly4and1open,cm3Vd=volumeofdeadspaceinsamplecellcontain-ingcatalyst(volumebetween2and3),cm3Vads(STP)x...
