ASTM_D_4926_-_20.pdf

Designation:D492620Standard Test Method forGamma Alumina Content in Catalysts and Catalyst CarriersContaining Silica and Alumina by X-ray Powder Diffraction1This standard is issued under the fixed designation D4926;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of gammaalumina and related transition aluminas in catalysts and cata-lyst carriers containing silica and alumina by X-ray powderdiffraction,using the diffracted intensity of the peak occurringat about 67 2 when copper K radiation is employed.1.2 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Summary of Test Method3.1 A sample of catalyst or catalyst carrier is calcined andground,and an X-ray powder diffraction pattern is obtainedunder specified conditions over the approximate range from 52to 76 2.The diffracted intensity above background for thepeak occurring at about 67 2 is compared to that of areference sample,after appropriate adjustments are made forscale settings and peak half-widths.4.Significance and Use4.1 This test method is for estimating the relative amount ofgamma alumina in calcined catalyst or catalyst carrier samples,assuming that the X-ray powder diffraction peak occurring atabout 67 2 is attributable to gamma alumina.Gammaalumina is defined as a transition alumina formed after heatingin the range from 500 to 550 C,and may include formsdescribed in the literature as eta,chi,and gamma aluminas.Delta alumina has a diffraction peak in the same region,but isformed above 850 C,a temperature to which most catalysts ofthis type are not heated.There are other possible componentswhich may cause some interference,such as alpha-quartz andzeolite Y,as well as aluminum-containing spinels formed atelevated temperatures.If the presence of interfering material issuspected,the diffraction pattern should be examined in greaterdetail.More significant interference may be caused by thepresence of large amounts of heavy metals or rare earths,whichexhibit strong X-ray absorption and scattering.Comparisonsbetween similar materials,therefore,may be more appropriatethan those between widely varying materials.5.Apparatus5.1 X-ray Powder Diffractometer Unit,with standardsample mount,Cu K radiation,monochromator,wide diver-gence and receiving slits(for example,3 and 0.15,respectively),goniometer speed of 0.5/min or equivalent,chart speed of about 0.5 cm min or equivalent,and scale orgain factors to provide conveniently measurable peaks.Com-puterized data acquisition equipment may also be used.NOTE1For diffractometers employing step scanning,convenientcorresponding conditions include a step size of 0.02 and a counting timeof 2.4 s step,which is equivalent to a scanning rate of 0.5/min.5.2 Calcination Furnace.5.3 Grinding Equipment,suitable for preparing samples formounting in the sample holder.6.Procedure6.1 Calcine the catalyst or catalyst carrier sample for 3 h at500 C.1This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommittee D32.01 on Physical-Chemical Properties.Current edition approved Oct.1,2020.Published October 2020.Originallyapproved in 1989.Last previous edition approved in 2015 as D4926 15.DOI:10.1520/D4926-20.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.6.2 Grind the sample