1、Designation: D4926 06 (Reapproved 2011)D4926 15Standard Test Method forGamma Alumina Content in Catalysts and Catalyst CarriersContaining Silica and Alumina by X-ray Powder Diffraction1This standard is issued under the fixed designation D4926; the number immediately following the designation indicat
2、es the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of
3、gamma alumina and related transition aluminas in catalysts and catalystcarriers containing silica and alumina by X-ray powder diffraction, using the diffracted intensity of the peak occurring at about 672 when copper K radiation is employed.1.2 The values stated in SI units are to be regarded as sta
4、ndard. 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 responsibilityof the user of this standard to establish appropriate safety and health practices and determine the ap
5、plicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Summary of Test Method3.1 A sample of catalyst or catalyst carrier is calcined and ground, and an X-ray pow
6、der diffraction pattern is obtained underspecified conditions over the approximate range from 52 to 76 2. The diffracted intensity above background for the peakoccurring at about 67 2 is compared to that of a reference sample, after appropriate adjustments are made for scale settings andpeak half-wi
7、dths.4. Significance and Use4.1 This test method is for estimating the relative amount of gamma alumina in calcined catalyst or catalyst carrier samples,assuming that the X-ray powder diffraction peak occurring at about 67 2 is attributable to gamma alumina. Gamma alumina isdefined as a transition a
8、lumina formed after heating in the range from 500 to 550C, and may include forms described in theliterature as eta, chi, and gamma aluminas. Delta alumina has a diffraction peak in the same region, but is formed above 850C,a temperature to which most catalysts of this type are not heated. There are
9、other possible components which may cause someinterference, such as alpha-quartz and zeolite Y, as well as aluminum-containing spinels formed at elevated temperatures. If thepresence of interfering material is suspected, the diffraction pattern should be examined in greater detail. More significanti
10、nterference may be caused by the presence of large amounts of heavy metals or rare earths, which exhibit strong X-ray absorptionand scattering. Comparisons between similar materials, therefore, may be more appropriate than those between widely varyingmaterials.5. Apparatus5.1 X-ray Powder Diffractom
11、eter Unit, with standard sample mount, Cu K radiation, monochromator, wide divergence andreceiving slits (for example, 3 and 0.15, respectively), goniometer speed of 0.5/min or equivalent, chart speed of about 0.5cm/min or equivalent, and scale or gain factors to provide conveniently measurable peak
12、s. Computerized data acquisitionequipment may also be used.1 This test method is under the jurisdiction of ASTM Committee D32 on Catalysts and is the direct responsibility of Subcommittee D32.01 on Physical-ChemicalProperties.Current edition approved April 1, 2011Dec. 1, 2015. Published April 2011Ja
13、nuary 2016. Originally approved in 1989. Last previous edition approved in 20062011 asD4926D492606(2011).06. DOI: 10.1520/D4926-06R11.10.1520/D4926-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Stan
14、dardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible
15、 to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West C
16、onshohocken, PA 19428-2959. United States1NOTE 1For diffractometers employing step scanning, convenient corresponding conditions include a step size of 0.02 and a counting time of 2.4s/step, which is equivalent to a scanning rate of 0.5/min.5.2 Calcination Furnace.5.3 Grinding Equipment, suitable fo
17、r preparing samples for mounting in the sample holder.6. Procedure6.1 Calcine the catalyst or catalyst carrier sample for 3 h at 500C.6.2 Grind the sample sufficiently (for example, 200 to 400 mesh) to enable it to be packed into a standard X-ray powderdiffractometer sample holder and mounted on the
18、 diffractometer.6.3 Obtain diffraction patterns for three samples over the approximate range from 52 to 76 2, using the conditions describedin 5.1.6.4 Measure the height of the 67 2 peak above background for the sample and the reference material to give H(sample) andH(reference), respectively.NOTE 2
19、Reference material may be prepared by calcining a high-purity sample of fine-particle boehmite for 3 h at 550C.7. Calculation7.1 The relative X-ray powder diffraction intensity of three samples, compared to a reference standard and expressed as percent,is calculated by use of the following equation:
20、100 Isample!Iref! 5Hsample!Href! 3Wsample!Wref! 3 Gref!Gsample!3100where:H(sample) = defined in 6.4,H(ref) = defined in 6.4,W(sample) /W(ref) = ratio of the peak width at half-height for the sample compared to that for the reference, andG(ref)/G(sample) = ratio of the instrument gain factor used to
21、record the peak for the sample to the gain factor used to recordthe peak for the reference. (Gain factor is often defined as the inverse of the product of the diffractometerscale setting and rate multiplier setting.7.2 The average of the three values calculated in 7.1 can be considered a measure of
22、gamma alumina content in the catalyst orcatalyst carrier if the measured sample peak is attributable to gamma alumina, the reference material is essentially pure gammaalumina, and the sample does not contain large amounts of heavy metals or rare earths. Caution should be observed in comparingresults
23、 for widely varying materials.7.3 A working or secondary reference material can be used as a matter of practical convenience. Should such a secondaryreference material be available, results as calculated in 7.1 relative to the first or primary reference material can be transformedto relate to the wo
24、rking reference material. Determine the relative X-ray powder diffraction intensity of the primary referencematerial relative to the secondary reference material, using an equation corresponding to that shown in 7.1 and expressing the ratioIR1/IR2 in fractional form. Multiply the result relative to
25、the primary reference material (100 I/IR1) by the factor just determinedabove (IR1/IR2) to get the result (100 I/IR2) relative to the secondary reference material. Identify the reference materials whenreporting the results.8. Precision and Bias38.1 PrecisionBased on the results of a multilaboratory,
26、 multisample study and using Practice E691, the within-laboratoryrepeatability was found to be 615 % (2S %) of the measured value, and the between-laboratory reproducibility was found to be624 % (2S %) of the measured value.8.2 BiasNo estimate of the bias of this test method is possible.3 Supporting
27、 data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D32-1027.D4926 1529. Keywords9.1 alumina; catalyst; catalyst carrier; gamma alumina; gamma alumina content; X-ray powder diffractionASTM International takes no position respecting the validi
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