ASTM D4926-06(2011)
(Test Method)Standard Test Method for Gamma Alumina Content in Catalysts Containing Silica and Alumina by X-ray Powder Diffraction
Standard Test Method for Gamma Alumina Content in Catalysts Containing Silica and Alumina by X-ray Powder Diffraction
SIGNIFICANCE AND USE
This test method is for estimating the relative amount of gamma alumina in calcined catalyst samples, assuming that the X-ray powder diffraction peak occurring at about 67 °2θ is attributable to gamma alumina. Gamma alumina is defined as a transition alumina formed after heating in the range from 500 to 550°C, and may include forms described in the literature as eta, chi, and gamma aluminas. Delta alumina has a diffraction peak in the same region, but is formed above 850°C, a temperature to which most catalysts of this type are not heated. There are other possible components which may cause some interference, such as alpha-quartz and zeolite Y, as well as aluminum-containing spinels formed at elevated temperatures. If the presence of interfering material is suspected, the diffraction pattern should be examined in greater detail. More significant interference may be caused by the presence of large amounts of heavy metals or rare earths, which exhibit strong X-ray absorption and scattering. Comparisons between similar materials, therefore, may be more appropriate than those between widely varying materials.
SCOPE
1.1 This test method covers the determination of gamma alumina and related transition aluminas in catalysts containing silica and alumina by X-ray powder diffraction, using the diffracted intensity of the peak occurring at about 67 °2θ when copper Kα radiation is employed.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4926 − 06(Reapproved 2011)
Standard Test Method for
Gamma Alumina Content in Catalysts Containing Silica and
Alumina by X-ray Powder Diffraction
This standard is issued under the fixed designation D4926; 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 X-ray powder diffraction peak occurring at about 67 °2θ is
attributable to gamma alumina. Gamma alumina is defined as
1.1 This test method covers the determination of gamma
a transition alumina formed after heating in the range from 500
alumina and related transition aluminas in catalysts containing
to 550°C, and may include forms described in the literature as
silica and alumina by X-ray powder diffraction, using the
eta, chi, and gamma aluminas. Delta alumina has a diffraction
diffracted intensity of the peak occurring at about 67 °2θ when
peak in the same region, but is formed above 850°C, a
copper Kα radiation is employed.
temperature to which most catalysts of this type are not heated.
1.2 The values stated in SI units are to be regarded as
There are other possible components which may cause some
standard. No other units of measurement are included in this
interference, such as alpha-quartz and zeolite Y, as well as
standard.
aluminum-containing spinels formed at elevated temperatures.
1.3 This standard does not purport to address all of the
If the presence of interfering material is suspected, the diffrac-
safety concerns, if any, associated with its use. It is the tion pattern should be examined in greater detail. More
responsibility of the user of this standard to establish appro-
significant interference may be caused by the presence of large
priate safety and health practices and determine the applica- amounts of heavy metals or rare earths, which exhibit strong
bility of regulatory limitations prior to use.
X-ray absorption and scattering. Comparisons between similar
materials, therefore, may be more appropriate than those
2. Referenced Documents
between widely varying materials.
2.1 ASTM Standards:
5. Apparatus
E691 Practice for Conducting an Interlaboratory Study to
5.1 X-ray Powder Diffractometer Unit, with standard
Determine the Precision of a Test Method
sample mount, Cu Kα radiation, monochromator, wide diver-
3. Summary of Test Method gence and receiving slits (for example, 3° and 0.15°,
respectively), goniometer speed of 0.5°/min or equivalent,
3.1 A sample of catalyst is calcined and ground, and an
chart speed of about 0.5 cm/min or equivalent, and scale or
X-ray powder diffraction pattern is obtained under specified
gain factors to provide conveniently measurable peaks. Com-
conditions over the approximate range from 52 to 76 °2θ. The
puterized data acquisition equipment may also be used.
diffracted intensity above background for the peak occurring at
about 67 °2θ is compared to that of a reference sample, after
NOTE 1—For diffractometers employing step scanning, convenient
corresponding conditions include a step size of 0.02° and a counting time
appropriate adjustments are made for scale settings and peak
of 2.4 s/step, which is equivalent to a scanning rate of 0.5°/min.
half-widths.
5.2 Calcination Furnace.
4. Significance and Use
5.3 Grinding Equipment, suitable for preparing samples for
4.1 This test method is for estimating the relative amount of
mounting in the sample holder.
gamma alumina in calcined catalyst samples, assuming that the
6. Procedure
6.1 Calcine the catalyst sample for3hat 500°C.
This test method is under the jurisdiction of ASTM Committee D32 on
Catalysts and is the direct responsibility of Subcommittee D32.01 on Physical- 6.2 Grind the sample sufficiently (for example, 200 to 400
Chemical Properties.
mesh) to enable it to be packed into a standard X-ray powder
Current edition approved April 1, 2011. Published April 2011. Originally
diffractometer sample holder and mounted on the diffractome-
approved in 1989. Last previous edition approved in 2006 as D4926–06. DOI:
ter.
10.1520/D4926-06R11.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.3 Obtain diffraction patterns for three samples over the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approximate range
...
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