1、Designation: D4179 11Standard Test Method forSingle Pellet Crush Strength of Formed Catalysts andCatalyst Carriers1This standard is issued under the fixed designation D4179; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、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 determining the resistance offormed catalysts and catalyst carriers to compressive force an
3、dis applicable to regular catalyst shapes such as tablets andspheres. Extrudates, granular materials, and other irregularshapes are specifically excluded.1.2 This test method determines the average crush strengthin the range from 0 to 50 lbf (0 to 220 N). Some materials mayhave crush strengths above
4、 50 lbf (220N); the test method isapplicable to these materials, but the precision of the test is notknown.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are no
5、t considered standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior
6、to use.2. Referenced Documents2.1 ASTM Standards:2E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions
7、of Terms Specific to This Standard:3.1.1 pelletsany catalyst shapetablets, spheres, or othersimilar configurationthat is not otherwise excluded from thescope of this test method.3.1.2 tabletstableted cylindrical catalyst particles, eithersolid or hollow core, with lengths that do not vary from theme
8、an by more than 610 %.4. Summary of Test Method4.1 Individual pellets taken from a representative sample areplaced between two flat surfaces, subjected to a compressiveload, and the force required to crush the pellet is measured. Theprocedure is replicated and the average of all measurementstaken is
9、 determined.5. Significance and Use5.1 This test method is intended to provide informationconcerning the ability of a catalyst shape to retain physicalintegrity during use.6. Apparatus6.1 A suitable compression testing device is required, con-sisting of the following:6.1.1 Calibrated Gauge, marked f
10、or direct reading of theforce in pounds (newtons). Additionally, a suitable system(mechanical, hydraulic, or pneumatic) must be provided so thatthe rate of force application is both uniform and controllablewithin specified limits.6.1.2 Tool Steel Anvils, between which the sample will becrushed. The
11、faces of the tool steel anvils shall be smooth andfree from recesses or ridges that would interfere with uniformcontact along the major axis of the pellet. When testing tablets1This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommitt
12、ee D32.02 on Physical-Mechanical Properties.Current edition approved Oct. 1, 2011. Published November 2011. Originallyapproved in 1982. Last previous edition approved in 2006 as D417901(2006).DOI: 10.1520/D4179-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM C
13、ustomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.or spheres, the anvils may be of
14、 any convenient size or shapeas long as their length and width are greater than the corre-sponding dimensions of the tablet or pellet being tested (seeFig. 1).7. Sampling7.1 A test sample of 50 to 200 individual pieces shall beobtained from larger composites by riffling or splitting inaccordance wit
15、h STP 447A,3(paragraph 5.12) with the aim ofobtaining a representative sample that represents shape andsize distribution of the larger composite. The size of the sampleshall depend on the precision required and the homogeneity ofthe material being tested.7.2 Pretreat the test sample(s) at 400 6 15C
16、for not lessthan 3 h. Normally, this treatment can take place in air;however, in the case of materials that might react with air atelevated temperatures (such as prereduced catalysts) the heattreatment should take place in an inert atmosphere. Care shouldbe taken to ensure that the pretreatment does
17、 not alter theinherent strength or structure of the sample as evidenced bychanges in surface area or phase. Any modifications to pre-treatment conditions should be noted in the report.7.3 After heating, cool the test sample(s) in a desiccator orother suitable container to eliminate the possibility o
18、f moistureadsorption prior to testing.NOTE 1Since many catalyst formulations are strong adsorbents, theuse of 4A indicating (cobalt-treated) molecular sieves as a desiccatingmedium is suggested. Regenerate the desiccant at 220 to 260C, asrequired.8. Calibration and Standardization8.1 Prior to use, s
19、et the test apparatus to zero and calibratewith any commercially available force gauge with markedgraduations of no more than12 lbf (2 N) and having accuracytraceable to the National Institute of Standards andTechnology,or other similar authority.9. Procedure9.1 Remove from the desiccator only that
20、number of pelletsthat can be tested within a 10-min period. (WarningEnsurethat moisture pick-up in the 10-min period will not signifi-cantly affect the pellet crush strength.)9.2 Place a single catalyst pellet between the anvils of thecompression testing device. Orient each pellet in the samedirecti
21、on before crushing. For those pellets capable of beingtested in different orientations, report the one used. Fig. 1shows pellets in radial and axial orientations. Use tweezers,forceps, or other suitable device or procedure to prevent thetransfer of moisture from the operators hands to the piecebeing
22、 tested.9.3 Apply increasing force at a uniform rate in the range of1 to 10 lbf/s (4.4 to 44 N/s) until the pellet crushes or collapses.Compression of surface irregularities or limited fracturing of apellet followed by continued resistance to increasing load arenot to be used as criteria for determi
23、ning the endpoint of thistest.9.4 Read and record, to the nearest one-half graduation, theforce indicated on the calibrated dial of the apparatus at theinstant of collapse.9.5 Separate the anvils and remove all residue with a softcloth or brush. Ensure that the faces of the anvils are free fromadher
24、ing particles.9.6 Repeat steps 9.2 through 9.5 until all pellets in thesample have been crushed. Record the crush strength for eachpellet tested.10. Calculation10.1 Calculate the average crush strength ( X), retaining onemore decimal place than the recorded values, as follows:Xlbf N! 5 (X!/n! (1)whe
25、re:(X = the sum of all observed crush strengths andn = the number of pellets crushed.10.2 Calculate the standard deviation of the n readings tothree significant digits as follows:S 5( X 2 X!2n 2 1lbf N! (2)where:S = standard deviation of the individual strengthvalues and(X X)2= sum of the squares of
26、 the deviations of eachrecorded reading from the average strength.NOTE 2Many calculators are programmed to perform these opera-tions and to report average and standard deviation directly. It is importantto verify that the program chosen uses the n 1 denominator rather thann in calculating standard d
27、eviation.11. Report11.1 Report the average crush strength to one more decimalplace than the recorded data on the individual strengths. For3STP 447A, Manual on Test Sieving Methods, ASTM International, WestConshohocken, PA 19428.FIG. 1 Radial and Axial CrushD4179 112pellets capable of being tested in
28、 different orientations, the oneused should be reported.11.2 Report the 80 % spread (that is, the range within which80 % of the individual pellet strengths are expected to fall,assuming that individual pellets form a normal distribution).Calculate as follows:80 % spread 5 X6 1.28S (3)11.3 Report the
29、 95 % reliability of the average reported in11.1. This is the uncertainty inherent in the reported average,expressed as the range within which 95 % of the averages of aninfinite number of test samples of n pellets would be expectedto fall were they to be similarly drawn from the same lot andtested.
30、Calculate as follows:95 % reliability 5 X6 1.96 S/=n (4)11.4 Report the applied rate of force increase, if available.12. Precision and Bias412.1 Test ProgramAn interlaboratory study was con-ducted in which the named property was measured in twoseparate test materials in six separate laboratories. Pr
31、acticeE691, modified for nonuniform data sets, was followed for thedata reduction. Analysis details are in the research report.12.2 PrecisionPairs of test results obtained by a proce-dure similar to that described in the study are expected to differin absolute value by less than 2.772 S, where 2.772
32、 S is the95 % probability interval limit on the difference between twotest results, and S is the appropriate estimate of standarddeviation. Definitions and usage are given in TerminologyE456 and Practice E177, respectively.Test Result (ConsensusMean) lbf95 % Repeatability Inter-val (Within Laborator
33、y)lbf (% of mean)95 % Reproducibility Inter-val (Between Laborato-ries) lbf (% of mean)20.19 (Spheres) 1.22 (6.03) 1.76 (8.74)16.50 (Tablets) 1.00 (6.03) 2.77 (16.8)12.3 BiasThis test method is without known bias.13. Keywords13.1 catalyst; crush strength; single pelletASTM International takes no pos
34、ition respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibil
35、ity.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to AS
36、TM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address
37、 shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610
38、-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D32-1004 and RR:D32-1024.D4179 113
