ASTM_D_8352_-_20.pdf

Designation:D835220Standard Test Method forDetermination of Relative Crystallinity of Zeolite Beta byX-Ray Diffraction1This standard is issued under the fixed designation D8352;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 a procedure for determinationof the relative crystallinity of zeolite Beta containing samplesusing selected peaks from the X-ray diffraction(XRD)patternof 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 zeoliteBeta to intensity of the corresponding portion of the pattern ofa reference zeolite Beta.The intensity ratio,expressed as apercentage,is then labeled percent XRD relative crystallinityof zeolite Beta.This type of comparison is commonly used inzeolite technology and is often referred to as percent crystal-linity.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:2E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Summary of Test Method3.1 This method applies to zeolite Beta samples withaverage crystallite size 150 nm.XRD patterns of the samplezeolite Beta and the reference zeolite Beta are obtained underthe same conditions.From these patterns,there is a choice fromtwo procedures for calculation of relative crystallinity ofzeolite Beta.3.2 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 about20.0 and 24.0 2.33.3 Procedure B(Peak Height Method)A comparison ismade of the absolute peak heights(sample versus reference)ofthe 22.5 2 peak.4.Significance and Use4.1 Zeolite Beta is a siliceous zeolite that can be crystallizedwith SiO2/Al2O3ratio greater than 20.Zeolite Beta,uponmodification to the H-cation form in a post-crystallization step,has been used in catalytic NOx reduction,isomerization ofwaxes,alkylation of aromatics,hydrocarbon adsorption fromexhaust gas emission,etc.4.2 This X-ray procedure is designed to allow a reporting ofthe relative degree of crystallinity upon manufacture of zeoliteBeta.The relative crystallinity of zeolite Beta number hasproven useful 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 zeolite Beta can resultfrom changes in distribution of electron density within the unitcell of the zeolite Beta.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.4.3.2 Type of cations and extent of their presence(thesecations may also affect the absorption of X rays by the zeoliteBeta sample).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 quaternary ammonium cations that can function as atemplate for crystallization of the zeolite Beta structure.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.1,2020.Published December 2020.DOI:10.1520/D8352-20.2For 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.4.3.4