1、Designation: D3942 03 (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 re
2、vision, 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 faujasi
3、te 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.
4、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, associate
5、d 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 toDeterm
6、ine 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.
7、Significance and Use4.1 Zeolites 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
8、 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, d
9、istinguishes 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 compo
10、sition 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 me
11、thod 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 su
12、ch 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 t
13、ubes such asmolybdenum can be used.NOTE 1A 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 a
14、nd 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, ww
15、w.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,
16、 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 A
17、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 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,
18、finely ground or ball-milled to a particlediameter less than 5 m as determined by microscope. NISToffers a Standard Reference Material (silicon) as an X-rayinternal standard (SMR 640) suitable for powder diffractionmeasurements.7. Procedure7.1 Place about 1.5 g of powdered zeolite sample in thedryin
19、g oven at 110C for 1 h.NOTE 2The drying step eliminates excess water from the sample priorto equilibration at constant-humidity hydration. Most catalyst samples,when received, will not contain excess water. Some sensitive samples mayrequire a lower activation temperature.7.2 Blend1gofpowdered zeolit
20、e sample with about 0.05 gof silicon in a mortar and grind until intimately mixed. Place athin bed of the mixed sample in the hydrator for at least 16 h.Some samples may require a longer equilibration time.7.3 Pack the hydrated sample in the diffractometer mount.7.4 Determine the X-ray diffraction p
21、attern across the rangefrom 50 to 60 2.NOTE 3Smaller slits are desirable for better peak resolution.NOTE 4In some catalyst samples, the zeolite reflections at about 53.4and 57.8 2 may be of insufficient intensity for accurate measurement.When this occurs, the diffraction pattern should be determined
22、 in theinterval 20 to 32 2.CuK consists of the composite of Cu K1and CuK2. The wavelength for Cu K is a weighted average of those of the twocomponents and is appropriate for use only when the components overlapso completely as to show no evidence of existence of more than onediffraction peak. In the
23、 frequent case where the resolution is too poor to becertain that the Cu K1value should be used but where peak distortion isevident, the value of peak location is taken as the midpoint at one-quarterpeak height, measured from the base up, and the wavelength for Cu K isused.NOTE 5If the instrument so
24、ftware has the ability to remove the CuK2contribution, it should be used when employing the low anglereflections (in the 20 to 32 range).7.5 Measure the angle of the zeolite reflections at about53.4 and 57.8 2 and that of the 56.1 silicon reflection to atleast two decimal places. For noncomputerized
25、 systems, if boththe two Cu K1and Cu K2reflections are clearly apparent,measure the angle of reflection peak (Cu K1) as the midpointat34 peak height.NOTE 6When low intensity prevents use of these high-anglereflections, as for example with equilibrium catalysts containing rare earthelements, measure
26、the strong zeolite reflections near 23.5, 26.9, and31.2 and the silicon reflection at 28.5 2 (Cu K).8. Calculation8.1 Correct the measured reflection angles for the zeolite byadding to each the quantity (calculated minus measured angleof the silicon reflection). When the silicon reflection of Cu K1r
27、adiation is measured, the calculated angle is 56.123 2; withCu K, the calculated angle is 56.173 2.NOTE 7The corresponding calculated angles when lower anglereflections must be used are 28.443 2 (Cu K1) and 28.467 2 (Cu K).8.2 Convert the corrected angles of reflection to d-spacingvalues using the e
28、quation:dhkl52sin(1)where:dhkl= distance between reflecting planes having the Millerindices hkl, (nm 10), and = wavelength of X-ray radiation which is 1.54178 (0.154178 nm) for Cu K and 1.54060 (0.154060nm) for Cu K1. Note that the angle of reflectionmeasured from the X-ray diffraction pattern is 2,
29、while the angle used in this calculation is only .48.3 Calculate the unit cell dimension, a, of the zeolite usingthe equation:a 5 $dhkl!2h21k21l2!%1/2(2)where the sum (h2+k2+12) of the respective zeolitereflections has the following values:5Reflection (h2+k2+12)57.8 2 24353.4 21131.2 7526.9 5623.5 4
30、3NOTE 8Certain components of a catalyst matrix can interfere withindividual peaks. For example, quartz may interfere with the reflection at26.9. When an interference occurs, other reflections should be used in thecalculation.8.4 Average the values of a calculated from more than onereflection.8.5 An
31、example of a determination can be shown from theX-ray diffraction pattern of a NaY sample, Fig. 1.CuK1(peak) and Cu K2(shoulder) are readily apparent on all threedesignated reflections, so that Cu K1values will be used in thecalculation. The angle of the peak of the reflection is measuredas follows:
32、Degrees 2Measured Corrected (h2+k2+12) (a, )58.197 58.215 243 24.68356.105 56.123 silicon 53.872 53.890 211 24.69124.687 averageThe correction factor in the above calculation is 56.123(calculated for Si) 56.105 (measured) = 0.018 and is sim-ply added to the measured angle of the two zeolite reflecti
33、ons.A d-spacing value for each of these two reflections is obtainedfrom the standard Cu K1tables (8.2) and values of the unitcell dimension, a, are then calculated according to the equationin 8.3.9. Report9.1 Report the following information.4Conversion tables exist and are commonly used for calcula
34、ting d-spacings. Forexample, see Fang, J. H. and Bloss, F. D., X-Ray Diffraction Tables, SouthernIllinois University Press, Carbondale, IL. 1966.5For a complete listing of hkl values in the range, 5 to 55 2, see Broussard, L.and Shoemaker, D. P., Journal of the American Chemical Society, Vol 82, 196
35、0, p.1041.D3942 03 (2013)29.1.1 Unit cell dimension, a, in Angstroms. (10 Ang-stroms = 1 nm.)9.1.2 The reflections used in the calculation.10. Precision and Bias610.1 Test ProgramAn interlaboratory study was con-ducted in which nine laboratories participated. Practice E691was used for data reduction
36、. Details are in the research report.10.2 The following criteria should be used for judging theacceptability of the results:10.2.1 RepeatabilityDuplicate results by the same opera-tor should be considered suspect if they differ by more than0.02 (0.002 nm).10.2.2 ReproducibilityThe results by each of
37、 two labora-tories should be considered suspect if they differ by more than0.04 (0.004 nm).10.3 BiasSince an accepted value is not available, the biashas not been determined.11. Keywords11.1 catalyst; faujasite; unit cell; X-ray diffraction; zeoliteASTM International takes no position respecting the
38、 validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is
39、 subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Hea
40、dquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This st
41、andard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or
42、serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D32-1002.FIG. 1 X-Ray Diffraction Pattern of NaYD3942 03 (2013)3
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