ASTM D3942-03(2013)
(Test Method)Standard Test Method for Determination of the Unit Cell Dimension of a Faujasite-Type Zeolite
Standard Test Method for Determination of the Unit Cell Dimension of a Faujasite-Type Zeolite
SIGNIFICANCE AND USE
4.1 Zeolites Y and X, particularly for catalyst and adsorbent applications, are a major article of manufacture and commerce. Catalysts and adsorbents comprising these zeolites in various forms plus binder and other components have likewise become important. Y-based catalysts are used for fluid catalytic cracking (FCC) and hydrocracking of petroleum, while X-based adsorbents are used for desiccation, sulfur compound removal, and air separation.
4.2 The unit cell dimension of a freshly synthesized faujasite-type zeolite is a sensitive measure of composition which, among other uses, distinguishes between the two synthetic faujasite-type zeolites, X and Y. The presence of a matrix in a Y-containing catalyst precludes determination of the zeolite framework composition by direct elemental analysis.
4.3 Users of the test method should be aware that the correlation between framework composition and unit cell dimension is specific to a given cation form of the zeolite. Steam or thermal treatments, for example, may alter both composition and cation form. The user must therefore determine the correlation that pertains to his zeolite containing samples.3 In addition, one may use the test method solely to determine the unit cell dimension, in which case no correlation is needed.
4.4 Other crystalline components may be present in the sample whose diffraction pattern may cause interference with the selected faujasite-structure diffraction peaks. If there is reason to suspect the presence of such components, then a full diffractometer scan should be obtained and analyzed to select faujasite-structure peaks free of interference.
SCOPE
1.1 This test method covers the determination of the unit cell dimension of zeolites having the faujasite crystal structure, including synthetic Y and X zeolites, their modifications such as the various cation exchange forms, and the dealuminized, decationated, and ultra stable forms of Y. These zeolites have cubic symmetry with a unit cell parameter usually within the limits of 24.2 and 25.0 Å (2.42 and 2.50 nm).
1.2 The samples include zeolite preparation in the various forms, and catalysts and adsorbents containing these zeolites. The zeolite may be present in amounts as low as 5 %, such as in a cracking catalyst.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
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Designation: D3942 − 03 (Reapproved 2013)
Standard Test Method for
Determination of the Unit Cell Dimension of a Faujasite-
Type Zeolite
This standard is issued under the fixed designation D3942; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope formsplusbinderandothercomponentshavelikewisebecome
important. Y-based catalysts are used for fluid catalytic crack-
1.1 This test method covers the determination of the unit
ing (FCC) and hydrocracking of petroleum, while X-based
celldimensionofzeoliteshavingthefaujasitecrystalstructure,
adsorbents are used for desiccation, sulfur compound removal,
including synthetic Y and X zeolites, their modifications such
and air separation.
as the various cation exchange forms, and the dealuminized,
decationated, and ultra stable forms of Y. These zeolites have 4.2 The unit cell dimension of a freshly synthesized
cubic symmetry with a unit cell parameter usually within the faujasite-type zeolite is a sensitive measure of composition
limits of 24.2 and 25.0 Å (2.42 and 2.50 nm). which, among other uses, distinguishes between the two
synthetic faujasite-type zeolites, X and Y. The presence of a
1.2 The samples include zeolite preparation in the various
matrixinaY-containingcatalystprecludesdeterminationofthe
forms, and catalysts and adsorbents containing these zeolites.
zeolite framework composition by direct elemental analysis.
The zeolite may be present in amounts as low as 5%, such as
in a cracking catalyst. 4.3 Users of the test method should be aware that the
correlation between framework composition and unit cell
1.3 This standard does not purport to address all of the
dimension is specific to a given cation form of the zeolite.
safety concerns, if any, associated with its use. It is the
Steam or thermal treatments, for example, may alter both
responsibility of the user of this standard to establish appro-
composition and cation form. The user must therefore deter-
priate safety and health practices and determine the applica-
mine the correlation that pertains to his zeolite containing
bility of regulatory limitations prior to use.
samples. In addition, one may use the test method solely to
2. Referenced Documents
determinetheunitcelldimension,inwhichcasenocorrelation
2 is needed.
2.1 ASTM Standards:
E691Practice for Conducting an Interlaboratory Study to 4.4 Other crystalline components may be present in the
Determine the Precision of a Test Method sample whose diffraction pattern may cause interference with
the selected faujasite-structure diffraction peaks. If there is
3. Summary of Test Method
reason to suspect the presence of such components, then a full
diffractometer scan should be obtained and analyzed to select
3.1 A sample of the zeolite Y or X, or catalyst containing
faujasite-structure peaks free of interference.
zeolite is mixed with powdered silicon. The zeolite unit cell
dimension is calculated from the X-ray diffraction pattern of
5. Apparatus
the mixture, using the silicon reflections as a reference.
5.1 X-Ray Diffractometer, able to scan at 0.25° 2θ/min. 2θ
4. Significance and Use
values in the following discussions were based on data
4.1 ZeolitesYandX,particularlyforcatalystandadsorbent obtained with a copper tube, although other tubes such as
applications,areamajorarticleofmanufactureandcommerce.
molybdenum can be used.
Catalysts and adsorbents comprising these zeolites in various
NOTE 1—A step-scanning accessory, to scan at a rate of 0.25° or less
2θ/min, will increase the accuracy of the determination and will facilitate
measurement in samples of low zeolite content.
This test method is under the jurisdiction of ASTM Committee D32 on
Catalysts and is the direct responsibility of Subcommittee D32.05 on Zeolites.
Current edition approved Dec. 1, 2013. Published December 2013. Originally
approved in 1980. Last previous edition approved in 2008 as D3942–03 (2008). Three correlations have been published for pure synthetic faujasite-type
DOI: 10.1520/D3942-03R13. zeolites in the sodium or calcium form: Breck, D. W. and Flanigen, E. M. in “
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Molecular Sieves,” Society of Chemical Industry , London, 1968, p. 47, Wright A.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM C., Rupert, J. P. and Granquist W. T. Amer. Mineral., Vol 53, 1968, p. 1293; and
Standards volume information, refer to the standard’s Document Summary page on Dempsy,E.,Kuehl,G.H.,andOlson,D.H.,JournalofthePhysicalChemistry,Vol
the ASTM website. 73, 1968, p. 387.
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D3942 − 03 (2013)
NOTE 7—The corresponding calculated angles when lower angle
5.2 Drying Oven, set at 110°C.
reflectionsmustbeusedare28.443°2θ(CuKα )and28.467°2θ(CuKα).
5.3 Hydrator, maintained at 35% relative humidity by a
8.2 Convert the corrected angles of reflection to d-spacing
saturated solution of salts such as CaCl ·6H O maintained at
2 2
values using the equation:
23°C 6 3°C.
λ
d 5 (1)
hkl
6. Reagents and Materials
2sinθ
6.1 Siliconpowder,finelygroundorball-milledtoaparticle
where:
diameter less than 5 µm as determined by microscope. NIST
d = distance between reflecting planes having the Miller
hkl
offers a Standard Reference Material (silicon) as an X-ray
indices hkl, Å(nm×10), and
internal standard (SMR 640) suitable for powder diffraction
λ = wavelength of X-ray radiation which is 1.54178 Å
measurements.
(0.154178 nm) for Cu Kα and 1.54060 Å (0.154060
nm) for Cu Kα . Note that the angle of reflection
7. Procedure
measured from the X-ray diffraction pattern is 2θ,
7.1 Place about 1.5 g of powdered zeolite sample in the
while the angle used in this calculation is only θ.
drying oven at 110°C for 1 h.
8.3 Calculate the unit cell dimension, a, of the zeolite using
the equation:
NOTE2—Thedryingstepeliminatesexcesswaterfromthesampleprior
to equilibration at constant-humidity hydration. Most catalyst samples,
2 2 2 2 1/2
a 5 $~d ! ~h 1k 1l !% (2)
hkl
whenreceived,willnotcontainexcesswater.Somesensitivesamplesmay
2 2 2
req
...
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