ASTM D4926-06

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D4926–06
Standard Test Method for
Gamma Alumina Content in Catalysts Containing Silica and
1
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 4. Significance and Use
1.1 This test method covers the determination of gamma 4.1 This test method is for estimating the relative amount of
alumina and related transition aluminas in catalysts containing gamma alumina in calcined catalyst samples, assuming that the
silica and alumina by X-ray powder diffraction, using the X-ray powder diffraction peak occurring at about 67 °2u is
diffracted intensity of the peak occurring at about 67 °2u when attributable to gamma alumina. Gamma alumina is defined as
copper Ka radiation is employed. a transition alumina formed after heating in the range from 500
1.2 The values stated in SI units are to be regarded as to 550°C, and may include forms described in the literature as
standard. No other units of measurement are included in this eta, chi, and gamma aluminas. Delta alumina has a diffraction
standard. peak in the same region, but is formed above 850°C, a
1.3 This standard does not purport to address all of the temperature to which most catalysts of this type are not heated.
safety concerns, if any, associated with its use. It is the There are other possible components which may cause some
responsibility of the user of this standard to establish appro- interference, such as alpha-quartz and zeolite Y, as well as
priate safety and health practices and determine the applica- aluminum-containing spinels formed at elevated temperatures.
bility of regulatory limitations prior to use. If the presence of interfering material is suspected, the diffrac-
tion pattern should be examined in greater detail. More
2. Referenced Documents
significant interference may be caused by the presence of large
2
2.1 ASTM Standards:
amounts of heavy metals or rare earths, which exhibit strong
E691 Practice for Conducting an Interlaboratory Study to X-ray absorption and scattering. Comparisons between similar
Determine the Precision of a Test Method
materials, therefore, may be more appropriate than those
between widely varying materials.
3. Summary of Test Method
5. Apparatus
3.1 A sample of catalyst is calcined and ground, and an
X-ray powder diffraction pattern is obtained under specified
5.1 X-ray Powder Diffractometer Unit, with standard
conditions over the approximate range from 52 to 76 °2u. The sample mount, Cu Ka radiation, monochromator, wide diver-
diffracted intensity above background for the peak occurring at
gence and receiving slits (for example, 3° and 0.15°, respec-
about 67 °2u is compared to that of a reference sample, after tively), goniometer speed of 0.5°/min or equivalent, chart
appropriate adjustments are made for scale settings and peak
speed of about 0.5 cm/min or equivalent, and scale or gain
half-widths. factors to provide conveniently measurable peaks. Computer-
ized data acquisition equipment may also be used.
NOTE 1—For diffractometers employing step scanning, convenient
1
corresponding conditions include a step size of 0.02° and a counting time
This test method is under the jurisdiction of ASTM Committee D32 on
Catalysts and is the direct responsibility of Subcommittee D32.01 on Physical- of 2.4 s/step, which is equivalent to a scanning rate of 0.5°/min.
Chemical Properties.
5.2 Calcination Furnace.
Current edition approved April 1, 2006. Published April 2006. Originally
approved in 1989. Last previous edition approved in 2001 as D4926–89(2001). 5.3 Grinding Equipment, suitable for preparing samples for
DOI: 10.1520/D4926-06.
mounting in the sample holder.
2
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
6. Procedure
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 6.1 Calcine the catalyst sample for3hat 500°C.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
D4926–06
6.2 Grind the sample sufficiently (for example, 200 to 400 if the measured sample peak is attributable to gamma alumina,
mesh) to enable it to be packed into a standard X-ray powder the reference material is essentially pure gamma alumina, and
diffractometer sample holder and mounted on the diffractome- the sample does not contain large amounts of heavy metals or
ter. r
...