Designation:D4926−06(Reapproved2011)StandardTestMethodforGammaAluminaContentinCatalystsContainingSilicaandAluminabyX-rayPowderDiffraction1ThisstandardisissuedunderthefixeddesignationD4926;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1ThistestmethodcoversthedeterminationofgammaaluminaandrelatedtransitionaluminasincatalystscontainingsilicaandaluminabyX-raypowderdiffraction,usingthediffractedintensityofthepeakoccurringatabout67°2uwhencopperKaradiationisemployed.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2E691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethod3.SummaryofTestMethod3.1Asampleofcatalystiscalcinedandground,andanX-raypowderdiffractionpatternisobtainedunderspecifiedconditionsovertheapproximaterangefrom52to76°2u.Thediffractedintensityabovebackgroundforthepeakoccurringatabout67°2uiscomparedtothatofareferencesample,afterappropriateadjustmentsaremadeforscalesettingsandpeakhalf-widths.4.SignificanceandUse4.1Thistestmethodisforestimatingtherelativeamountofgammaaluminaincalcinedcatalystsamples,assumingthattheX-raypowderdiffractionpeakoccurringatabout67°2uisattributabletogammaalumina.Gammaaluminaisdefinedasatransitionaluminaformedafterheatingintherangefrom500to550°C,andmayincludeformsdescribedintheliteratureaseta,chi,andgammaaluminas.Deltaaluminahasadiffractionpeakinthesameregion,butisformedabove850°C,atemperaturetowhichmostcatalystsofthistypearenotheated.Thereareotherpossibleco...
