ASTM_D_5758_-_01_2011e1.pdf

Designation:D575801(Reapproved 2011)1Standard Test Method forDetermination of Relative Crystallinity of Zeolite ZSM-5 byX-Ray Diffraction1This standard is issued under the fixed designation D5758;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.1NOTEUpdated ZSM-5 powder availability footnote editorially in October 2011.1.Scope1.1 This test method covers a procedure for determinationof the relative crystallinity of zeolite ZSM-5 using selectedpeaks from the X-ray diffraction pattern of the zeolite.1.2 The test method provides a number that is the ratio ofintensity of a portion of the XRD pattern of the sample ZSM-5to intensity of the corresponding portion of the pattern of areference ZSM-5.The intensity ratio,expressed as apercentage,is then labeled percent XRD relative crystallinity/ZSM-5.This type of comparison is commonly used in zeolitetechnology and is often referred to as percent crystallinity.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:2D3906 Test Method for Determination of Relative X-rayDiffractionIntensitiesofFaujasite-TypeZeolite-Containing MaterialsD5357 Test Method for Determination of Relative Crystal-linity of Zeolite Sodium A by X-ray DiffractionE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Summary of Test Method3.1 XRD patterns of the sample ZSM-5 and the referenceZSM-5 are obtained under the same conditions.From thesepatterns,there is a choice from two procedures for calculationof relative crystallinity/ZSM-5.3.1.1 Procedure A(Integrated Peak Area Method)A com-parison is made of the sums of intensities(sample versusreference)of the strong peaks,having maxima between about23.1 and 24.3 2.3.1.2 Procedure B(Peak Height Method)A comparison ismade of the absolute peak heights(sample versus reference)ofthe 24.3 2 peak.4.Significance and Use4.1 ZSM-5 is a siliceous zeolite that can be crystallized withSiO2/Al2O3ratio in the range of 20 to greater than 1000.ZSM-5,upon modification to the H-cation form(HZSM-5)ina post-crystallization step,has been used since the 1970s as ashape selective,acid-site catalyst for petroleum refining andpetrochemicals production,including such processes asalkylation,isomerization,fluid cracking catalysis(FCC),andmethanol-to-gasoline.The most siliceous member of theZSM-5 family,sometimes called silicalite,is hydrophobic andit is used for selective sorption of organic molecules fromwater-containing systems.4.2 This X-ray procedure is designed to allow a reporting ofthe relative degree of crystallization upon manufacture ofZSM-5.The relative crystallinity/ZSM-5 number has provenuseful in technology,research,and specifications.4.3 The Integrated Peak Area Method(Procedure A)ispreferred over the Peak Height Method(Procedure B)since itcalculates XRD intensity as a sum from several peaks ratherthan utilizing just one peak.Drastic changes in intensity ofindividual peaks in the XRD pattern of ZSM-5 can result fromchanges in distribution of electron density within the unit cellof the ZSM-5 zeolite.The electron density distribution isdependent upon the following factors:4.3.1 Extent of filling of pores with guest molecules and thenature of these guest molecules.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 Oct.1,2011.Published December 2011.Originallyapproved in 1995.Last previous edition approved in 2007 as D575801(2007)1.DOI:10.1520/D5758-01R11E01.2For 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 States1 4.3.2 Type of cations and extent of their presence(thesecations may also affect the absorption of X rays by the ZSM-5sample).4.3.3 In this XRD method,the guest molecule H2O com-pletes the filling of the pores.Other guest molecule types mayalso be present,including one of numerous amines,diamines,and quarternary ammonium cations that can function as atemplate for crystallization of the ZSM-5 structure.4.3.4 Because of the factors mentioned in 4.3.1 to 4.3.3 thatcould vary the intensities of t