ASTM D4926-89(1994)e1

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: D 4926 – 89 (Reapproved 1994)
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 D 4926; 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.
e NOTE—Section 9 was added editorially in April 1994.
1. Scope temperature to which most catalysts of this type are not heated.
There are other possible components which may cause some
1.1 This test method covers the determination of gamma
interference, such as alpha-quartz and zeolite Y, as well as
alumina and related transition aluminas in catalysts containing
aluminum-containing spinels formed at elevated temperatures.
silica and alumina by X-ray powder diffraction, using the
If the presence of interfering material is suspected, the diffrac-
diffracted intensity of the peak occurring at about 67°2u when
tion pattern should be examined in greater detail. More
copper Ka radiation is employed.
significant interference may be caused by the presence of large
1.2 This standard does not purport to address all of the
amounts of heavy metals or rare earths, which exhibit strong
safety concerns, if any, associated with its use. It is the
X-ray absorption and scattering. Comparisons between similar
responsibility of the user of this standard to establish appro-
materials, therefore, may be more appropriate than those
priate safety and health practices and determine the applica-
between widely varying materials.
bility of regulatory limitations prior to use.
5. Apparatus
2. Referenced Documents
5.1 X-Ray Powder Diffractometer Unit, with standard
2.1 ASTM Standards:
sample mount, Cu Ka radiation, monochromator, wide diver-
E 691 Practice for Conducting an Interlaboratory Study to
gence and receiving slits (for example, 3° and 0.15°, respec-
Determine the Precision of a Test Method
tively), goniometer speed of 0.5°/min or equivalent, chart
3. Summary of Test Method speed of about 0.5 cm/min or equivalent, and scale or gain
factors to provide conveniently measurable peaks.
3.1 A sample of catalyst is calcined and ground, and an
X-ray powder diffraction pattern is obtained under specified
NOTE 1—For diffractometers employing step scanning, convenient
conditions over the approximate range from 52 to 76°2u. The
corresponding conditions include a step size of 0.02° and a counting time
of 2.4 s/step, which is equivalent to a scanning rate of 0.5°/min.
diffracted intensity above background for the peak occurring at
about 67°2u is compared to that of a reference sample, after
5.2 Calcination Furnace.
appropriate adjustments are made for scale settings and peak
5.3 Grinding Equipment, suitable for preparing samples for
half-widths.
mounting in the sample holder.
4. Significance and Use
6. Procedure
4.1 This test method is for estimating the relative amount of
6.1 Calcine the catalyst sample for3hat 500°C.
gamma alumina in calcined catalyst samples, assuming that the
6.2 Grind the sample sufficiently (for example, 200 to 400
X-ray powder diffraction peak occurring at about 67°2u is
mesh) to enable it to be packed into a standard X-ray powder
attributable to gamma alumina. Gamma alumina is defined as
diffractometer sample holder and mounted on the diffractome-
a transition alumina formed after heating in the range from 500
ter.
to 550°C, and may include forms described in the literature as
6.3 Obtain diffraction patterns for three samples over the
eta, chi, and gamma aluminas. Delta alumina has a diffraction
approximate range from 52 to 76°2u, using the conditions
peak in the same region, but is formed above 850°C, a
described in 5.1.
6.4 Measure the height of the 67°2u peak above background
for the sample and the reference material to give H (sample)
This test method is under the jurisdiction of ASTM Committee D-32 on
and H (reference), respectively.
Catalysts and is the direct responsibility of Subcommitte
...