Designation:D4179−11
Standard Test Method for
Single Pellet Crush Strength of Formed Catalysts and Catalyst Carriers1
This standard is issued under thefixed designation D4179;the number immediately following the designation indicates the year of original adoption or,in the ca of revision,the year of last revision.A number in parenthes indicates the year of last reapproval.A superscript epsilon(´)indicates an editorial change since the last revision or reapproval.
1.Scope
1.1This test method covers determining the resistance of formed catalysts and catalyst carriers to compressive force and is applicable to regular catalyst shapes such as tablets and spheres.Extrudates,granular materials,and other irregular shapes are specifically excluded.
1.2This test method determines the average crush strength in the range from0to50lbf(0to220N).Some materials may have crush strengths above50lbf(220N);the test method is applicable to the materials,but the precision of the test is not known.
1.3The values stated in inch-pound units are to be regarded as standard.The values given in parenthes are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.4This standard does not purport to address all of the safety concerns,if any,associated with its u.It is the responsibility of the ur of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to u.
2.Referenced Documents
2.1ASTM Standards:2
E177Practice for U of the Terms Precision and Bias in ASTM Test Methods
E456Terminology Relating to Quality and Statistics
E691Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3.Terminology
3.1Definitions of Terms Specific to This Standard:
3.1.1pellets—any catalyst shape—tablets,spheres,or other similar configuration—that is not otherwi excluded from the scope of this test method.
3.1.2tablets—tableted cylindrical catalyst particles,either solid or hollow core,with lengths that do not vary from the mean by more than610%.
4.Summary of Test Method
4.1Individual pellets taken from a reprentative sample are placed between twoflat surfaces,subjected to a compressive load,and the force required to crush the pellet is measured.The procedure is replicated and the average of all measurements taken is determined.
5.Significance and U
5.1This test method is intended to provide information concerning the ability of a catalyst shape to retain physical integrity during u.
6.Apparatus
6.1A suitable compression testing device is required,con-sisting of the following:
6.1.1Calibrated Gauge,marked for direct reading of the force in pounds(newtons).Additionally,a suitable system (mechanical,hydraulic,or pneumatic)must be provided so that the rate of force application is both uniform and controllable within specified limits.
6.1.2Tool Steel Anvils,between which the sample will be crushed.The faces of the tool steel anvils shall be smooth and free from recess or ridges that would interfere with uniform contact along the major axis of the pellet.When testing tablets or spheres,the anvils may be of any convenient size or shape
1This test method is under the jurisdiction of ASTM Committee D32on
Catalysts and is the direct responsibility of Subcommittee D32.02on Physical-
Mechanical Properties.
Current edition approved Oct.1,2011.Published November2011.Originally
approved in1982.Last previous edition approved in2006as D4179–01(2006).
交换生英语
DOI:10.1520/D4179-11.
2For referenced ASTM standards,visit the ASTM website,www.astm,or
contact ASTM Customer Service at rvice@astm.For Annual Book of ASTM
Standards volume information,refer to the standard’s Document Summary page on
the ASTM website.
Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959.United States
as long as their length and width are greater than the corre-sponding dimensions of the tablet or pellet being tested (e Fig.1).7.Sampling
7.1A test sample of 50to 200individual pieces shall be obtained from larger composites by riffling or splitting in accordance with STP 447A,3(paragraph 5.12)with the aim of obtaining a reprentative sample that reprents shape and size distribution of the larger composite.The size of the sample shall depend on the precision required and the homogeneity of the material being tested.
7.2Pretreat the test sample(s)at 400615°C for not less than 3h.Normally,this treatment can take place in air;however,in the ca of materials that might react with air at elevated temperatures (such as prereduced catalysts)the heat treatment should take place in an inert atmosphere.Care should be taken to ensure that the pretreatment does not alter the inherent strength or structure of the sample as evidenced by changes in surface area or pha.Any modifications to pre-treatment conditions should be noted in the report.
7.3After heating,cool the test sample(s)in a desiccator or other suitable container to eliminate the possibility of moisture adsorption prior to testing.
N OTE 1—Since many catalyst formulations are strong adsorbents,the u of 4A indicating (cobalt-treated)molecular sieves as a desiccating medium is suggested.Regenerate the desiccant at 220to 260°C,as required.
生物进化的原因
8.Calibration and Standardization联通积分换话费
8.1Prior to u,t the test apparatus to zero and calibrate
with any commercially available force gauge with marked graduations of no more than 1⁄2lbf (2N)and having accuracy
traceable to the National Institute of Standards and Technology,or other similar authority.9.Procedure
real未删减版
9.1Remove from the desiccator only that number of pellets that can be tested within a 10-min period.(Warning—Ensure that moisture pick-up in the 10-min period will not signifi-cantly affect the pellet crush strength.)
9.2Place a single catalyst pellet between the anvils of the compression testing device.Orient each pellet in the same direction before crushing.For tho pellets capable of being tested in different orientations,report the one ud.Fig.1shows pellets in radial and axial orientations.U tweezers,forceps,or other suitable device or procedure to prevent the transfer of moisture from the operator’s hands to the piece being tested.
9.3Apply increasing force at a uniform rate in the range of 1to 10lbf/s (4.4to 44N/s)until the pellet cru
shes or collaps.Compression of surface irregularities or limited fracturing of a pellet followed by continued resistance to increasing load are not to be ud as criteria for determining the endpoint of this test.
9.4Read and record,to the nearest one-half graduation,the force indicated on the calibrated dial of the apparatus at the instant of collap.
9.5Separate the anvils and remove all residue with a soft cloth or brush.Ensure that the faces of the anvils are free from adhering particles.
9.6Repeat steps 9.2through 9.5until all pellets in the sample have been crushed.Record the crush strength for each pellet tested.10.Calculation
10.1Calculate the average crush strength (X
¯),retaining one more decimal place than the recorded values,as follows:
X
¯lbf ~N !5~(X !/~n !
(1)
where:
^X =the sum of all obrved crush strengths and n =the number of pellets crushed.10.2Calculate the standard deviation of the n readings to three significant digits as follows:
S 5
Œ
(~X 2X
¯!2
四十四绕口令
n 21
lbf ~N !(2)
where:S =standard deviation of the individual strength
values and
^(X −X
大闹西游¯)2=sum of the squares of the deviations of each recorded reading from the average strength.
N OTE 2—Many calculators are programmed to perform the operations and to report average and standard deviation directly.It is important to verify that the program chon us the n −1denominator rather than n in calculating standard deviation.
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STP 447A,Manual on Test Sieving Methods ,ASTM International,West Conshohocken,PA
19428.
FIG.1Radial and Axial
Crush
11.Report
11.1Report the average crush strength to one more decimal place than the recorded data on the individual strengths.For pellets capable of being tested in different orientations,the one ud should be reported.
11.2Report the 80%spread (that is,the range within which 80%of the individual pellet strengths are expected to fall,assuming that individual pellets form a normal distribution).Calculate as follows:
80%spread 5X
¯61.28S (3)
11.3Report the 95%reliability of the average reported in
11.1.This is the uncertainty inherent in the reported average,expresd as the range within which 95%of the averages of an infinite number of test samples of n pellets would be expected to fall were they to be similarly drawn from the same lot and tested.Calculate as follows:
95%reliability 5X
¯61.96S /=n (4)
11.4Report the applied rate of force increa,if available.12.Precision and Bias 4
12.1Test Program—An interlaboratory study was con-ducted in which the named property was measured in two
parate test materials in six parate laboratories.Practice E691,modified for nonuniform data ts,
was followed for the data reduction.Analysis details are in the rearch report.12.2Precision—Pairs of test results obtained by a procedure similar to that described in the study are expected to differ in absolute value by less than 2.772S ,where 2.772S is the 95%probability interval limit on the difference between two test results,and S is the appropriate estimate of standard deviation.Definitions and usage are given in Terminology E456and Practice E177,respectively.
Test Result (Connsus Mean)lbf 95%Repeatability Inter-val (Within Laboratory)
lbf (%of mean)95%Reproducibility Inter-val (Between Laboratories)
lbf (%of mean)20.19(Spheres) 1.22(6.03) 1.76(8.74)16.50(Tablets)
1.00(6.03)
八月迷情电影
2.77(16.8)
12.3Bias—This test method is without known bias.13.Keywords
13.1catalyst;crush strength;single pellet
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be obtained by requesting Rearch Report RR:D32-1004and
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