1、Designation: D5758 01 (Reapproved 2015)Standard 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 ca
2、se 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 zeol
3、ite 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, ex
4、pressed 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.
5、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-rayDiffraction Intensities o
6、f Faujasite-Type Zeolite-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
7、 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.
8、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) ofth
9、e 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-sit
10、e 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 sorptio
11、n 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 Pea
12、k 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 ele
13、ctron 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.4.3.2 Type of cations and extent of their presence (thesecations may also affe
14、ct 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,1This test method is under the jurisdiction of ASTM Committee D32 onCatalyst
15、s and is the direct responsibility of Subcommittee D32.05 on Zeolites.Current edition approved Dec. 1, 2015. Published December 2015. Originallyapproved in 1995. Last previous edition approved in 2011 as D575801(2011). DOI:10.1520/D5758-01R15.2For referenced ASTM standards, visit the ASTM website, w
16、ww.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 States1and
17、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 the XRD peaks in ZSM-5, thisXRD method will provide the best determination of relativecrystallinity when t
18、he reference ZSM-5 and sample ZSM-5have a similar history of preparation and composition.4.4 ZSM-5 can exist with either orthorhombic or mono-clinic symmetry, depending upon the composition of theprecursor gel or post-crystallization modification conditions, orboth. In the orthorhombic type, the XRD
19、 peaks centered atabout 23.1 and 23.8 2 are usually split into doublets, whereasthe less symmetric monoclinic type may show a further split ofthese peaks into triplets. The peak area intensities of thesepeaks are unaffected by the crystalline form. The XRD peak at24.3 2 for the orthorhombic form is
20、a singlet and hence is themost suitable for the Peak Height Method (Procedure B). If the24.3 peak is split (doublet in the monoclinic form), then theIntegrated Peak Area Method (Procedure A) should be used.4.5 If crystalline phases other than ZSM-5 are present in thesample, their diffraction peaks m
21、ay overlap with some of theZSM-5 peaks selected for the Integrated Peak Area Method(ProcedureA). If there is reason to suspect the presence of suchcomponents, then the Peak Height Method (Procedure B)should be chosen for analysis provided that there is nointerference with the 24.3 2 peak that is use
22、d for thecalculation.5. Apparatus5.1 X-ray Diffractometer, equipped with computerized dataacquisition and reduction capability, or with a strip chartrecorder, and using copper K-alpha radiation.5.2 Drying Oven, set at 105 6 5C.5.3 Hydrator (Laboratory Desiccator), maintained at about58 % relative hu
23、midity by a saturated solution of sodiumbromide, NaBr.5.4 Planimeter.NOTE 1The planimeter will not be needed if the XRD instrument isequipped with computerized data acquisition and reduction capability.6. Reagents and Materials6.1 ZSM-5 Powder,3as reference standard, preferably witha mean particle d
24、iameter of less than 10 m.7. Procedure7.1 Carry out steps 7.2 through 7.4, in an identical manner,for both the sample ZSM-5 and the reference ZSM-5.7.2 Place about 1.5 g of finely divided ZSM-5 in the dryingoven at 105C for 2 h. Cool the sample in the hydrator and holdthere at room temperature and a
25、bout 58 % relative humidity forat least 16 h.NOTE 2Grinding of course-textured samples should be done gently.Overgrinding can lead to breaking up of fine crystals and destruction ofthe zeolite.NOTE 3Drying, followed by rehydration, results in filling the zeolitepores with water of hydration but with
26、out an excess of moisture residingon the surface of the zeolite particles.7.3 Pack the humidity-conditioned sample into an XRDsample holder.7.4 Obtain an XRD pattern of the reference ZSM-5 and alsoobtain a pattern of the sample ZSM-5 (in the same day), byscanning over the angle range from 11 to 32 2
27、 usinginstrument parameters best suited to the X-ray diffractometer.The scan rate should not be greater than 1.0/min. The scanrange includes the diffraction peaks that are to be used in thecalculation for relative crystallinity. The XRD pattern of thesample can also be used to check for crystalline
28、phases otherthan ZSM-5 that might be present and might interfere with theutility of the calculation of ProcedureA(see 4.5). Fig. 1 showsa pattern for the reference ZSM-5 (H+cation form) used in thetesting of this test method.7.4.1 If a strip chart recorder is used, set the chart drive at 20mm/min. S
29、elect the scale factor (for amplification) for thereference ZSM-5 pattern so that the strongest peak at 23.1 2is between 50 and 100 % of full scale. The same scale factorshould be used for the sample ZSM-5 pattern. However, if thesample gives considerably lower peak intensities, the scalefactor may
30、be reduced (amplification increased) in order toprovide reasonable peak heights.3Available from NIST as RM8852.FIG. 1 X-Ray Diffraction Wide Scan Pattern of Zeolite ZSM-5ASTM Z-20 (Reference)D5758 01 (2015)28. Calculation8.1 Procedure A (Integrated Peak Area Method)This cal-culation involves a compa
31、rison of the integrated peak areas inthe range of 22.5 to 25.0 2 (measured above background)from the patterns obtained in 7.4.8.1.1 Obtain an integrated peak area encompassing the threeto five strong peaks in the 22.5 to 25.0 2 range for both thesample ZSM-5 and the reference ZSM-5. The area is gene
32、rallydetermined in one of two ways:8.1.1.1 From the counts recorded by a digital integratingsystem that is used while obtaining the pattern.8.1.1.2 By measuring the area under the peaks with aplanimeter.8.1.2 Calculate the relative crystallinity using the equation:% XRD relative crystallinity ZSM-5
33、5SxSr3100 (1)where:Sx= integrated peak area for the sample ZSM-5, andSr= integrated peak area for the reference ZSM-5.8.2 Procedure B (Peak Height Method)This calculationinvolves a comparison of the peak heights at 24.3 2 (mea-sured above background) from the patterns obtained in 7.4.8.2.1 Construct
34、 a baseline from the center of the backgroundscatter at 21.2 2 to the center of the background scatter at25.0 2 on the XRD patterns (hardcopy or stripchart) of thesample ZSM-5 and reference ZSM-5. Determine the absoluteheights of the respective peaks centered at 24.3 2; that is,measure the height, i
35、n millimetres, from the baseline to theapex of the peak. Fig. 2 shows an example of the peak heightdetermination.8.2.2 Calculate the relative crystallinity using the equation:% XRD relative crystallinity ZSM-5 5HsHr3100 (2)where:Hs= peak height for the sample, andHr= peak height for the reference.NO
36、TE 4Peak area or peak heights determined by the techniques in8.1.1.2 or 8.2.1 must be obtained from XRD patterns that have a linearintensity scale, and must have a correction factor applied if the scalefactors used for the ZSM-5 reference and sample patterns are different; seeTest Method D3906 and D
37、5357.NOTE 5Some samples of zeolite may be slightly more crystalline thana chosen reference material. Thus relative crystallinity values greater than100 % may be obtained.NOTE 6Peak broadening in XRD patterns of zeolites can occur for avariety of reasons, including small crystal size (below about 0.2
38、 m),disorder, absorption, and inconsistent sample packing density. ZSM-5products can be manufactured having a wide range of mean crystal sizes,including less than 0.2 m. Thus the percent XRD relative crystallinity ofthe small crystal ZSM-5, when calculated by the Peak Height Method(Procedure B), may
39、 be erroneously low.9. Report9.1 Report the following information:9.1.1 Relative crystallinity of ZSM-5,9.1.2 The utilized procedure, that is, the Integrated PeakArea Method or the Peak Height Method, and9.1.3 Non-ZSM-5 peaks, if present (impurity identificaiton,if possible).10. Precision and Bias10
40、.1 Test ProgramAn interlaboratory study was con-ducted in which the named property was measured in twoseparate test materials in ten separate laboratories. PracticeE691, modified for non-uniform data sets, was followed for thedata reduction. Analysis details are in the Research Report.10.2 Precision
41、Pairs of test results obtained by a proceduresimilar to that described in the study are expected to differ inabsolute value by less than 2.772 S, where 2.772 S is the95 % probability interval limit on the difference between twotest results, and S is the appropriate estimate of standarddeviation. Def
42、initions and usage are given in Practices E456and E177, respectively. See Table 1.10.3 BiasThis test method is without known bias.11. Keywords11.1 crystallinity; X-ray diffraction; zeolite ZSM-5FIG. 2 X-Ray Diffraction Short Scan Pattern of Zeolite ZSM-5ASTM Z-20 (Reference) (for Peak Height MethodP
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48、-2600; http:/ 1 Precision DataCalculation Procedure Test Result(consensus mean)95 % Repeatability Interval(within laboratory)95 % Reproducibility Interval(between laboratories)Integrated peak area 95.62 % 2.19 % 5.04 %(2.29 % of mean) (5.27 % of mean)Peak height 91.11 % 5.33 % 10.42 %(5.84 % of mean) (11.44 % of mean)D5758 01 (2015)4
