ASTM D3942-97
(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
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 (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.
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.
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Designation: D 3942 – 97
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Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Determination of the Unit Cell Dimension of a Faujasite-
1
Type Zeolite
This standard is issued under the fixed designation D 3942; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4.2 The unit cell dimension of a freshly synthesized
faujasite-type zeolite is a sensitive measure of composition
1.1 This test method covers the determination of the unit
which, among other uses, distinguishes between the two
cell dimension of zeolites having the faujasite crystal structure,
synthetic faujasite-type zeolites, X and Y. The presence of a
including synthetic Y and X zeolites, their modifications such
matrix in a Y-containing catalyst precludes determination of the
as the various cation exchange forms, and the dealuminized,
zeolite framework composition by direct elemental analysis.
decationated, and ultra stable forms of Y. These zeolites have
4.3 Users of the method should be aware that the correlation
cubic symmetry with a unit cell parameter usually within the
between framework composition and unit cell dimension is
limits of 24.2 and 25.0 Å (2.42 and 2.50 nm).
specific to a given cation form of the zeolite. Steam or thermal
1.2 The samples include zeolite preparation in the various
treatments, for example, may alter both composition and cation
forms, and catalysts and adsorbents containing these zeolites.
form. The user must therefore determine the correlation that
The zeolite may be present in amounts as low as 5 %, such as
3
pertains to his zeolite containing samples. In addition, one
in a cracking catalyst.
may use the method solely to determine the unit cell dimen-
1.3 This standard does not purport to address all of the
sion, in which case no correlation is needed.
safety concerns, if any, associated with its use. It is the
4.4 Other crystalline components may be present in the
responsibility of the user of this standard to establish appro-
sample whose diffraction pattern may cause interference with
priate safety and health practices and determine the applica-
the selected faujasite-structure diffraction peaks. If there is
bility of regulatory limitations prior to use.
reason to suspect the presence of such components, then a full
2. Referenced Documents
diffractometer scan should be obtained and analyzed to select
faujasite-structure peaks free of interference.
2.1 ASTM Standards:
E 691 Practice for Conducting an Interlaboratory Study to
2 5. Apparatus
Determine the Precision of a Test Method
5.1 X-Ray Diffractometer, able to scan at 0.25° 2u/min. 2u
3. Summary of Test Method
values in the following discussions were based on data
3.1 A sample of the zeolite Y or X, or catalyst containing obtained with a copper tube, although other tubes such as
zeolite is mixed with powdered silicon. The zeolite unit cell
molybdenum can be used.
dimension is calculated from the X-ray diffraction pattern of
NOTE 1—A step-scanning accessory, to scan at a rate of 0.25° or less
the mixture, using the silicon reflections as a reference.
2u/min, will increase the accuracy of the determination and will facilitate
measurement in samples of low zeolite content.
4. Significance and Use
5.2 Drying Oven, set at 110°C.
4.1 Zeolites Y and X, particularly for catalyst and adsorbent
5.3 Hydrator, maintained at 35 % relative humidity by a
applications, are a major article of manufacture and commerce,
saturated solution of salts such as CaCl ·6H O maintained at
2 2
use of which has developed since the 1960s. Catalysts and
23°C 6 3°C.
adsorbents comprising these zeolites in various forms plus
binder and other components have likewise become important
6. Reagents and Materials
in this period. Y-based catalysts are used for fluid catalytic
6.1 Silicon powder, finely ground or ball-milled to a particle
cracking (FCC) and hydrocracking of petroleum, while
diameter less than 5 μm as determined by microscope. NIST
X-based adsorbents are used for desiccation, sulfur compound
removal, and air separation.
3
Three correlations have been published for pure synthetic faujasite-type
1
This test method is under the jurisdiction of ASTM Committee D-32 on zeolites in the sodium or calcium form: Breck, D. W. and Flanigen, E. M. in“
Catalysts and is the direct responsibility of Subcommittee D32.05 on Zeolites. Molecular Sieves”, Society of Chemical Industry, London, 1968, p. 47, Wright A. C.,
Current edition approved March 10, 1997. Publishe
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