1、Designation: D 3942 03Standard Test Method forDetermination of the Unit Cell Dimension of a Faujasite-Type Zeolite1This standard is issued under the fixed designation D 3942; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 stru
3、cture,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
4、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.
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:E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precisi
6、on of a Test Method23. 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 a
7、nd 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 for fluid cat
8、alytic 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 b
9、etween 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 method should be aware that the correlationbetween framework composition and unit cel
10、l dimension isspecific to a given cation form of the zeolite. Steam or thermaltreatments, for example, may alter both composition and cationform. The user must therefore determine the correlation thatpertains to his zeolite containing samples.3In addition, onemay use the method solely to determine t
11、he unit cell dimen-sion, in which case no correlation is 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 f
12、ulldiffractometer 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 2u/min. 2uvalues in the following discussions were based on dataobtained with a copper tube, although other tubes such asmolybdenu
13、m can be used.NOTE 1A step-scanning accessory, to scan at a rate of 0.25 or less2u/min, will increase the accuracy of the determination and will facilitatemeasurement in samples of low zeolite content.5.2 Drying Oven, set at 110C.1This test method is under the jurisdiction of ASTM Committee D32 onCa
14、talysts and is the direct responsibility of Subcommittee D32.05 on Zeolites.Current edition approved March 10, 2003. Published April 2003. Originallyapproved in 1980. Last previous edition approved in 1997 as D 394297.2Annual Book of ASTM Standards, Vol 14.02.3Three correlations have been published
15、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 Ol
16、son, D. H., Journal of the Physical Chemistry,Vol73, 1968, p. 387.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3 Hydrator, maintained at 35 % relative humidity by asaturated solution of salts such as CaCl26H2O maintained at23C 6
17、 3C.6. Reagents and Materials6.1 Silicon powder, 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 a
18、bout 1.5 g of powdered zeolite sample in thedrying 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 ac
19、tivation temperature.7.2 Blend1gofpowdered zeolite 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 diffracto
20、meter mount.7.4 Determine the X-ray diffraction pattern across the rangefrom 50 to 60 2u.NOTE 3Smaller slits are desirable for better peak resolution.NOTE 4In some catalyst samples, the zeolite reflections at about 53.4and 57.8 2u may be of insufficient intensity for accurate measurement.When this o
21、ccurs, the diffraction pattern should be determined in theinterval 20 to 32 2u.CuKa consists of the composite of Cu Ka1and CuKa2. The wavelength for Cu Ka is a weighted average of those of the twocomponents and is appropriate for use only when the components overlapso completely as to show no eviden
22、ce of existence of more than onediffraction peak. In the frequent case where the resolution is too poor to becertain that the Cu Ka1value 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
23、the wavelength for Cu Ka isused.NOTE 5If the instrument software has the ability to remove the CuKa2contribution, 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 2u and that of the 56.1 silicon r
24、eflection to atleast two decimal places. For noncomputerized systems, if boththe two Cu Ka1and Cu Ka2reflections are clearly apparent,measure the angle of reflection peak (Cu Ka1) as the midpointat34 peak height.NOTE 6When low intensity prevents use of these high-angle reflec-tions, as for example w
25、ith equilibrium catalysts containing rare earthelements, measure the strong zeolite reflections near 23.5, 26.9, and31.2 and the silicon reflection at 28.5 2u (Cu Ka).8. Calculation8.1 Correct the measured reflection angles for the zeolite byadding to each the quantity (calculated minus measured ang
26、leof the silicon reflection). When the silicon reflection of Cu Ka1radiation is measured, the calculated angle is 56.123 2u; withCu Ka, the calculated angle is 56.173 2u.NOTE 7The corresponding calculated angles when lower angle re-flections must be used are 28.443 2u (Cu Ka1) and 28.467 2u (Cu Ka).
27、8.2 Convert the corrected angles of reflection to d-spacingvalues using the equation:dhkl5l2 sin u(1)where:dhkl= distance between reflecting planes having the Millerindices hkl, (nm 3 10), andl = wavelength of X-ray radiation which is 1.54178 (0.154178 nm) for Cu Ka and 1.54060 (0.154060nm) for Cu K
28、a1. Note that the angle of reflectionmeasured from the X-ray diffraction pattern is 2u,while the angle used in this calculation is only u.48.3 Calculate the unit cell dimension, a, of the zeolite usingthe equation:a 5 $dhkl!2h21 k21 l2!%1/2(2)where the sum (h2+k2+12) of the respective zeolitereflect
29、ions has the following values:5Reflection (h2+k2+12)57.8 2u 24353.4 21131.2 7526.9 5623.5 43NOTE 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
30、 thecalculation.8.4 Average the values of a calculated from more than onereflection.8.5 An example of a determination can be shown from theX-ray diffraction pattern of a NaY sample, Fig. 1. CuKa1(peak) and Cu Ka2(shoulder) are readily apparent on allthree designated reflections, so that Cu Ka1values
31、 will be usedin the calculation. The angle of the peak of the reflection ismeasured as follows:Degrees 2uMeasured 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)
32、56.105 (measured) = 0.018 and is sim-ply added to the measured angle of the two zeolite reflections.A d-spacing value for each of these two reflections is obtainedfrom the standard Cu Ka1tables (8.2) and values of the unitcell dimension, a, are then calculated according to the equationin 8.3.64Conve
33、rsion tables exist and are commonly used for calculating 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 2u, see Broussard, L.and Shoemaker, D. P.,
34、Journal of the American Chemical Society, Vol 82, 1960, p.1041.6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D321002.D39420329. Report9.1 Report the following information.9.1.1 Unit cell dimension, a, in Angstroms. (10 Ang-st
35、roms = 1 nm.)9.1.2 The reflections used in the calculation.10. Precision and Bias10.1 Test ProgramAn interlaboratory study was con-ducted in which nine laboratories participated. Practice E 691was used for data reduction. Details are in the research report.10.2 The following criteria should be used
36、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 two labora-tories should be considered suspect if they differ by more than0.04
37、(0.004 nm).10.3 BiasSince an accepted value is not available, thebias has not been determined.11. Keywords11.1 catalyst; faujasite; unit cell; X-ray diffraction; zeoliteASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin
38、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 subject to revision at any time by the responsible technical committee and must
39、 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 Headquarters. Your comments will receive careful consideration at a meeting of ther
40、esponsible 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 standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700,
41、 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 serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 1 X-Ray Diffraction Pattern of NaYD3942033
