ASTM D3942-19

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Designation: D3942 − 03 (Reapproved 2013) D3942 − 19
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. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. 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 25.0 Å (2.42 and 2.50 nm).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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Summary of Test Method
3.1 A sample of the zeolite Y or X, or catalyst containing zeolite is mixed with powdered silicon. The zeolite unit cell dimension
is calculated from the X-ray diffraction pattern of the mixture, using the silicon reflections as a reference.
4. 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. In addition, one may use
the test method solely to determine the unit cell dimension, in which case no correlation is needed.
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, 2013April 1, 2019. Published December 2013May 2019. Originally approved in 1980. Last previous edition approved in 20082013 as
D3942 – 03 (2008).(2013). DOI: 10.1520/D3942-03R13.10.1520/D3942-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Three correlations have been published for pure synthetic faujasite-type zeolites in the sodium or calcium form: Breck, D. W.W., and Flanigen, E. M. in “ Molecular
M., “Molecular Sieves,” Society of Chemical Industry, , London, 1968, p. 47,47; Wright A. C., Rupert, J. P.P., and Granquist W. T.T., Amer. Mineral., Vol 53, 1968, p. 1293;
and Dempsy, E., Kuehl, G. H., and Olson, D. H., Journal of the Physical Chemistry, Vol 73, 1968, p. 387.
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D3942 − 19
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.
5. Apparatus
5.1 X-Ray Diffractometer, able to scan at 0.25° 2θ/min. 2θ values in the following discussions were based on data obtained with
a copper tube, although other tubes such as molybdenum can be used.
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.
NOTE 2—Modern analysis software might be used for the linear angle correction as well.
5.2 Drying Oven, set at 110°C.110 °C.
5.3 Hydrator, maintained at 35 % relative humidity by a saturated solution of salts such as CaCl ·6H O maintained at
2 2
23°C23 °C 6 3°C.3 °C.
6. Reagents and Materials
6.1 Silicon powder, finely ground or ball-milled to a particle diameter less than 5 μm as determined by microscope. NIST offers
a Standard Reference Material (silicon) as an X-ray internal standard (SMR 640) suitable for powder diffraction measurements.
7. Procedure
7.1 Place about 1.5 g of powdered zeolite sample in the drying oven at 110°C110 °C for 1 h.
NOTE 3—The drying step eliminates excess water from the sample prior to equilibration at constant-humidity hydration. Most catalyst samples, when
received, will not contain excess water. Some sensitive samples may require a lower activation temperature.
7.2 Blend 1 g of powdered zeolite sample with about 0.05 g of silicon in a mortar and grind until intimately mixed. Place a thin
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 pattern across the range from 50 to 60° 2θ.
NOTE 4—Smaller slits are desirable for better peak resolution.
NOTE 5—In some catalyst samples, the zeolite reflections at about 53.4° and
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