ASTM D3906-97
(Test Method)Standard Test Method for Determination of Relative X-ray Diffraction Intensities of Faujasite-Type Zeolite-Containing Materials
Standard Test Method for Determination of Relative X-ray Diffraction Intensities of Faujasite-Type Zeolite-Containing Materials
SCOPE
1.1 This test method covers determining relative zeolite diffraction intensities.
1.2 The term "zeolite" here is restricted to those zeolites having the faujasite crystal structure, including X and Y zeolites, the various cation exchange forms, and the dealuminized, decationated, and ultrastable forms. These zeolites have cubic symmetry with unit cell parameter within the limits 24.2 and 25.0 A (2.42 and 2.50 nm). The samples contemplated include zeolite preparations in the various forms and catalysts containing these zeolites.
1.3 The term "intensity of an X-ray powder diffraction (XRD) peak" is the "integral intensity," either the area of counts under the peak or the product of the peak height and the peak width.
1.4 The method provides a number that is the ratio of intensity of portions of the XRD pattern of the sample to intensity of the corresponding portion of the pattern of a reference zeolite, NaY. (Laboratories may use other zeolite, for example, REY as a secondary standard.) The intensity ratio, expressed as a percentage, is then labeled "% XRD intensity/NaY."
1.5 Under certain conditions such a ratio is the percent zeolite in the sample. These conditions include:
1.5.1 The zeolite in the sample is the same as the reference zeolite.
1.5.2 The absorption for the X-rays used is the same for the zeolite and the nonzeolite portions of the sample.
1.6 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 3906 – 97
Standard Test Method for
Determination of Relative X-ray Diffraction Intensities of
Faujasite-Type Zeolite-Containing Materials
This standard is issued under the fixed designation D 3906; 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 E 691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1.1 This test method covers the determination of relative
X-ray diffraction intensities of zeolites having the faujasite
3. Summary of Test Method
crystal structure, including synthetic Y and X zeolites, their
3.1 The XRD patterns of the zeolite containing sample and
modifications such as the various cation exchange forms, and
the reference sample (NaY), are obtained under the same
the dealuminized, decationated, and ultrastable forms of Y.
conditions. Intensities of the (533) peak (23.5° with Cu Ka
These zeolites have cubic symmetry with a unit cell parameter
radiation) are compared to provide “% XRD intensity/NaY
˚
usually within the limits of 24.2 and 25.0A (2.42 and 2.50 nm).
(533).” If the XRD pattern of the zeolite is sufficiently strong,
1.2 The samples include zeolite preparations in the various
a comparison of the sums of intensities of eight peaks is used
forms, and catalysts and adsorbents containing these zeolites.
to give “% crystallinity.”
1.3 The term “intensity of an X-ray powder diffraction
(XRD) peak” is the “integral intensity,” either the area of
4. Significance and Use
counts under the peak or the product of the peak height and the
4.1 Zeolites Y and X, particularly for catalyst and adsorbent
peak width.
applications, are a major article of manufacture and commerce,
1.4 The method provides a number that is the ratio of
use of which has developed since the 1960s. Catalysts and
intensity of portions of the XRD pattern of the sample to
adsorbents comprising these zeolites in various forms plus
intensity of the corresponding portion of the pattern of a
binder and other components have likewise become important
reference zeolite, NaY. (Laboratories may use a modified Y or
in this period. Y-based catalysts are used for fluid catalytic
X, for example, REY as a secondary standard.) The intensity
cracking (FCC) and hydrocracking of petroleum, while
ratio, expressed as a percentage, is then labeled “% XRD
X-based adsorbents are used for desiccation, sulfur compound
intensity/NaY.”
removal, and air separation.
1.5 Under certain conditions such a ratio is the percent
4.2 This X-ray procedure is designed to monitor these Y and
zeolite in the sample. These conditions include:
X zeolites and catalysts and adsorbents, providing a number
1.5.1 The zeolite in the sample is the same as the reference
more or less closely related to percent zeolite in the sample.
zeolite.
This number has proven useful in technology, research, and
1.5.2 The absorption for the X-rays used is the same for the
specifications.
zeolite and the nonzeolite portions of the sample.
4.3 Drastic changes in intensity of individual peaks in the
1.6 This standard does not purport to address all of the
XRD patterns of Y and X can result from changes of distribu-
safety concerns, if any, associated with its use. It is the
tion of electron density within the unit cell of the zeolite. The
responsibility of the user of this standard to establish appro-
electron density distribution is dependent upon the extent of
priate safety and health practices and determine the applica-
filling of pores in the zeolite with guest molecules, and on the
bility of regulatory limitations prior to use.
nature of the guest molecules. In this XRD method, the guest
2. Referenced Documents molecule H O completely fills the pores. Intensity changes
may also result if some or all of the cations in Y and X are
2.1 ASTM Standards:
exchanged by other cations.
E 177 Practice for Use of the Terms Precision and Bias in
2 4.3.1 Because of the factors mentioned in 4.3 that could
ASTM Test Methods
vary the intensities of the XRD peaks, this XRD method will
E 456 Terminology Relating to Quality and Statistics
provide the best determination of relative crystallinity when the
reference and sample have a similar history of preparation and
composition.
This test method is under the jurisdiction of ASTM Committee D-32 on
Catalysts and is the direct responsibility of Subcommittee D32.05 on Zeolites.
4.4 Corrections are possible that can make this XRD
Current edition approved March 10, 1997. Published October 1997. Originally
method accurate for measuring percent zeolite in many specific
published as D 3906 – 80. Last previous edition D 3906 – 91.
situations. These corrections are well known to those skilled in
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 3906
X-ray diffraction. It is not practical to specify those corrections 8.6 Obtain a second XRD pattern by scanning over a small
here. angle range at ⁄4 °/min.
8.6.1 If a strip chart recorder is used, set the drive at 20
5. Apparatus
mm/min. The same scale factors used in Step 8.4 are suitable.
5.1 X-ray Diffractometer, equipped with a strip chart re-
The preferred angle range is from 22.5 to 25° 2u, the (533)
corder or with computerized data acquisition and reduction
peak. Fig. 3 shows such a pattern for NaY. If interference rules
capability, using copper K-alpha radiation.
out this range, choose for this step (for both the sample and the
5.2 Drying Oven, set at 110°C.
reference patterns) one of the following angle ranges:
5.3 Hydrator (Glass Laboratory Desiccator), maintained at
14.0 to 17.0°, (331) peak
35 % relative humidity by a saturated solution of salt, such as
19.0 to 22.0°, (440) peak
CaCl ·6H O.
2 2 25.5 to 28.0°, (642) peak
5.4 Planimeter.
NOTE 4—These ranges in Step 8.6 each are of such width that two or
NOTE 1—This planimeter may not be needed if the XRD instrument is more zeolite peaks are included. Such wide ranges are specified to allow
equipped with a digital integrating circuit. for the variation in peak position over the range of unit cell dimensions
24.2 to 25.0 Å (2.42 to 2.50 mm) and to provide a background reading on
6. Reagents and Materials
each side of the main peak. Within each range the major zeolite peak will
be the desired one. See Appendix X1 of peak positions.
6.1 NaY Powder and RE Exchanged Y Powder, as reference
standards.
9. Calculation
7. Sampling 9.1 Obtain an integral peak intensity for each of the eight
peaks (measured above background) chosen from the patterns
7.1 Conduct sampling by splitting a large portion of the
from 8.4, for both the sample and reference, in one of three
sample and reference material homogeneously.
ways:
7.2 Divide the sample and reference finely to permit pack-
9.1.1 By approximating the area under the peak as the
ing of the materials into XRD sample holders.
product of peak height and peak width at half height, or
NOTE 2—The best test to determine if grinding is required is to try to
9.1.2 By measuring the area under the peak with a planime-
pack the sample in the holder. Overgrinding can lead to breaking up of fine
ter, or
crystals and even destruction of zeolite.
9.1.3 From the counts recorded by a digital integrating
system.
8. Procedure
9.2 Approximate Area Calculation:
8.1 Carry out the following steps, 8.2 through 8.5, in an
9.2.1 A scale factor correction, SFC, is the ratio of the scale
identical manner for both the sample and the reference mate-
factor used for the sample pattern, SF , to that used for the
X
rial, NaY.
reference pattern, SF . Thus, SFC = SF /SF . Scale factors are
R X R
8.2 Place about 3 to5gofthe sample in the drying oven at
usually expressed in terms of counts per second corresponding
110°C for 1 h. Cool the sample in the hydrator and hold at
to full scale on the recorder. They are related inversely to
room temperature and 35 % relative humidity for at least 16 h.
amplification.
NOTE 3—Drying, followed by rehydration, results in filling the zeolite
9.2.2 Measure the width of the (533) or alternative peaks
pores with water of hydration but without an excess of moisture residing
obtained in Step 8.6. The width is measured at half the peak
on the surface of the zeolite particles.
height, that is, half way between the background and the peak
8.3 Pack the humidity-conditioned sample into an XRD
maximum. Obtain the width factor, WF, which is the ratio of
sample holder.
the peak width of the sample, W , to that of the NaY reference
X
8.4 Obtain a first XRD pattern by scanning over the angle
material, W . Thus, WF = W /W .
R X R
range from 14 to 35° 2u at 1°/min and using other instrument
NOTE 5—Peak broadening occurs for a variety of reasons. Pertinent for
parameters best suited to the diffractometer.
zeolite are the following: crystals may be of limited size, below 0.2 μm;
8.4.1 If a strip chart recorder is used, set the chart drive at 10
crystals may contain disorder; crystals may exist with a range of unit cell
mm/min. Select the scale factor (amplification) for the NaY
dimensions; and diffraction may originate from varying depths below the
reference pattern so that the strong (533) peak at 23.6° is
sample surface, limited by absorption, and related to density of packing of
the sample.
between 50 and 100 % of full scale. For the sample the scale
factor may be reduced (amplification increased) to provide
9.2.3 The objective of the method, a value for “% XRD
reasonable peak heights. If possible the height of the (533)
intensity/NaY,” is obtained in this step. This involves a
peak for the sample should be at least 10 % of full scale. Fig.
comparison of the sums of peak heights (measured above
1 shows such patterns for the reference NaY and for a
background) from the patterns obtained in Step 8.4. The ratio
zeolite-containing catalyst.
of these sums must be corrected for difference in scale factor,
8.5 If this first pattern of the sample contains XRD peaks of
by use of SFC as determined in Step 9.2.1, and for difference
some nonfaujasite components, it must be established whether
in peak widths, by use of WF as determined in Step 9.2.2. Eight
this m
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