ASTM_D_3942_-_03_2013.pdf

Designation:D394203(Reapproved 2013)Standard Test Method forDetermination of the Unit Cell Dimension of a Faujasite-Type Zeolite1This standard is issued under the fixed designation D3942;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 the unitcell dimension of zeolites having the faujasite crystal structure,including synthetic Y and X zeolites,their modifications suchas the various cation exchange forms,and the dealuminized,decationated,and ultra stable forms of Y.These zeolites havecubic symmetry with a unit cell parameter usually within thelimits of 24.2 and 25.0 (2.42 and 2.50 nm).1.2 The samples include zeolite preparation in the variousforms,and catalysts and adsorbents containing these zeolites.The zeolite may be present in amounts as low as 5%,such asin a cracking catalyst.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 and health practices and determine the applica-bility of regulatory limitations prior to use.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 the zeolite Y or X,or catalyst containingzeolite is mixed with powdered silicon.The zeolite unit celldimension is calculated from the X-ray diffraction pattern ofthe mixture,using the silicon reflections as a reference.4.Significance and Use4.1Zeolites Y and X,particularly for catalyst and adsorbentapplications,are a major article of manufacture and commerce.Catalysts and adsorbents comprising these zeolites in variousforms plus binder and other components have likewise becomeimportant.Y-based catalysts are used for fluid catalytic crack-ing(FCC)and hydrocracking of petroleum,while X-basedadsorbents are used for desiccation,sulfur compound removal,and air separation.4.2 The unit cell dimension of a freshly synthesizedfaujasite-type zeolite is a sensitive measure of compositionwhich,among other uses,distinguishes between the twosynthetic faujasite-type zeolites,X and Y.The presence of amatrix in a Y-containing catalyst precludes determination of thezeolite framework composition by direct elemental analysis.4.3 Users of the test method should be aware that thecorrelation between framework composition and unit celldimension is specific to a given cation form of the zeolite.Steam or thermal treatments,for example,may alter bothcomposition and cation form.The user must therefore deter-mine the correlation that pertains to his zeolite containingsamples.3In addition,one may use the test method solely todetermine the unit cell dimension,in which case no correlationis needed.4.4 Other crystalline components may be present in thesample whose diffraction pattern may cause interference withthe selected faujasite-structure diffraction peaks.If there isreason to suspect the presence of such components,then a fulldiffractometer scan should be obtained and analyzed to selectfaujasite-structure peaks free of interference.5.Apparatus5.1 X-Ray Diffractometer,able to scan at 0.25 2/min.2values in the following discussions were based on dataobtained with a copper tube,although other tubes such asmolybdenum can be used.NOTE1A step-scanning accessory,to scan at a rate of 0.25 or less2/min,will increase the accuracy of the determination and will facilitatemeasurement in samples of low zeolite content.1This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommittee D32.05 on Zeolites.Current edition approved Dec.1,2013.Published December 2013.Originallyapproved in 1980.Last previous edition approved in 2008 as D3942 03(2008).DOI:10.1520/D3942-03R13.2For 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.3Three correlations have been published for pure synthetic faujasite-typezeolites in the sodium or calcium form:Breck,D.W.and Flanigen,E.M.in“Molecular Sieves,”Society of Chemical Industry,London,1968,p.47,Wright A.C.,Rupert,J.P.and Granquist W.T.Amer.Mineral.,Vol 53,1968,p.1293;andDempsy,E.,Kuehl,G.H.,and Olson,D.H.,Journal of the Physical Chemistry,Vol73,1968,p.387.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2 Drying Oven,set at 110C.5.3 Hydrator,maintained at 35%relative humidity by asaturated solution of salts such as CaCl26H2O maintained at23C 6 3C.6.Reagents and Materials6.1 Silicon powder,finely ground