1、Designation: D 4438 85 (Reapproved 2007)Standard Test Method forParticle Size Distribution of Catalytic Material by ElectronicCounting1This standard is issued under the fixed designation D 4438; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of particlesize distribution of catalyst and cataly
3、st carrier particles usingan electroconductive sensing method and is one of severalvaluable methods for the measurement of particle size.1.2 The range of particle sizes investigated was 20 to 150m (see IEEE/ASTM SI 10) equivalent spherical diameter.The technique is capable of measuring particles abo
4、ve andbelow this range. The instrument used for this method is anelectric current path of small dimensions that is modulated byindividual particle passage through an aperture, and producesindividual pulses of amplitude proportional to the particlevolume.1.3 This standard does not purport to address
5、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 to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specificati
6、on for Reagent WaterE 177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodIEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System3. Summary
7、 of Test Method3.1 Acarefully dispersed, dilute suspension of the sample ina beaker filled with an electrolyte is placed in the countingposition on the instrument sample stand. The suspension isforced through a restricting aperture. Each passing particle isrecorded on an electronic counter, and the
8、data are accumulatedaccording to selected particle size intervals for subsequentprocessing.3.2 The instrument response is proportional to liquid dis-placement by the particle volume. Equivalent spherical diam-eter is commonly used to express the particle size.4. Significance and Use4.1 This test met
9、hod can be used to determine particle sizedistributions for material specifications, manufacturing control,and research and development work in the particle size rangeusually encountered in fluidizable cracking catalysts.5. Apparatus35.1 Electronic Particle Counter, with sample stand andstirring mot
10、or.5.2 Aperture Tubes, with varying diameters. The diameterrequired is dependent upon the particle size distribution of thesample. Generally, any given tube will cover a particle sizerange from 2 to 40 % of its aperture diameter.5.3 Ultrasonic Tank, 100 W.5.4 Beaker, 100-mL.5.5 Graduated Glass Pipet
11、, 5-mL.5.6 Wash Bottles.5.7 Membrane Filtering Device with 0.22-m filters.5.8 Round-Bottom Sample Beakers, 250-mL.5.9 Micro-Riffler or Chute Riffler.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall c
12、onform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of
13、the determination.1This test method is under the jurisdiction of ASTM Committee D32 onCatalysts and is the direct responsibility of Subcommittee D32.02 on Physical-Mechanical Properties.Current edition approved April 1, 2007. Published April 2007. Originallyapproved in 1985. Last previous edition ap
14、proved in 2001 as D 443885(2001)e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Supporting data have been
15、 filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D32-1011.4“Reagent Chemicals, American Chemical Society Specifications,” Am. Chemi-cal Soc., Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see “Anal
16、ar Standards for Laboratory U.K.Chemicals,” BDH Ltd., Poole, Dorset, and the “United States Pharmacopeia.”1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be unde
17、rstood to mean reagent water conformingto Specification D 1193, Type II.6.3 ElectrolyteDissolve 10.0 g of reagent grade sodiumchloride (NaCl) in 1 L of distilled or deionized water and filtertwice through a 0.22-m filter.NOTE 1Commercially available Electrolyte solution of the sameconcentration can
18、also be used, but should be filtered for apertures smallerthan 100 m.6.4 Wash WaterDistilled or deionized water, twice filteredthrough a 0.22-m filter. Electrolyte may also be used as washwater.6.5 Calibration Spheres5, Near monosized, having a relativestandard deviation from the mean of less than 5
19、 %, or equiva-lent, as certified by the manufacturer.7. Procedure7.1 Follow instrument manufacturers instruction manualfor instrument settings.7.2 Follow the manufacturers instructions for calibratingeach aperture and electrolyte combination that will be used.7.3 Before each analysis, using the wash
20、 bottle and filteredwash water, wash all surfaces coming in contact with thesample.7.4 Place 150 to 200 mL of electrolyte in a round-bottombeaker on the sample stand with the stirring rod turningmoderately fast. Position the stirring blades near the bottom ofthe beaker and increase the stirrer speed
21、 to a rate just below airbubble formation (Note 2). Follow the instruction manual andtake several background counts. If they exceed the limit in themanual for the aperture in use, refilter the electrolyte and flushthe glassware. If the background is due to electrical interfer-ence, the instrument ma
22、nufacturers recommendations forsample should not be used when it can disintegrate fragileprimary particles.NOTE 2Proper adjustment of the position and speed of the stirrer willprevent the loss of large particles by settling and formation of air bubblesduring counting.7.4.1 Transfer the sample into a
23、 250-mL round-bottombeaker containing about 200 mL of clean electrolyte. Be sureall the sample is transferred.7.4.2 Place the sample and beaker (from 7.4.1)intheinstrument sampling stand. Adjust the stirring blades close tothe bottom of the round-bottom beaker so that they effectivelysweep the botto
24、m of the beaker to maintain all particlesuniformly in suspension.7.4.3 During stirring, using a 5-mL pipet, transfer 2 mL ofthe sample suspension (from 7.4.2) to another 250-mL round-bottom beaker containing 200 mL of clean electrolyte. Be sureall the contents in the pipet are transferred.7.4.4 Remo
25、ve the beaker (from 7.4.1) from the samplingstand. Flush the outside of the aperture tube, the stirrer, andouter electrode. Place the sample and beaker from 7.4.3 in thesampling stand. Adjust the stirring blades close to the bottomof the round-bottom beaker so that they effectively sweep thebottom o
26、f the beaker again. Increase the stirrer speed moder-ately. Check for particle settling by visually observing thestirring system with a flashlight and viewing the surfaceperpendicular to the bottom. If particles are observed settling,increase stirring rate without generating air bubbles or increaset
27、he electrolyte viscosity, or both.NOTE 3Electrolyte viscosity can be increased, for example, by addingfiltered glycerol up to 30 % by volume.7.4.5 Initiate a preliminary count and check that the totalcount is in the range suggested in the manufacturers instruc-tions to avoid excessive coincidence lo
28、ss. If the count is toohigh, adjust by diluting with clean electrolyte.7.4.6 Initiate an analysis count, and accumulate and processdata in accordance with the manufacturers instructions. Forincreased precision take a total of three sets of data and averagethem. If the resulting data in differential
29、volume form showmore than a few percent in the smallest active channel,additional data may be obtained using a smaller aperture afterlarge particles are scalped from the sample. Data from bothapertures may then be combined, as described in the instrumentmanufacturers instruction manual, although thi
30、s step is be-yond the scope of this test method.8. Presentation of Data8.1 The instrument measures the volume of each particle.Assuming all the particles in the sample have the same density,relative volume and weight can be considered to be inter-changeable; therefore, cumulative and differential vo
31、lume orweight percent can be printed or graphed directly from theaccumulated data.8.2 Results for samples containing mixed densities shouldbe expressed as volume percent instead of weight percent andcannot be compared to a direct weight analysis method.NOTE 4Comparisons with other techniques have be
32、en found to begood for spherical particles within the sensing range covered by theaperture or apertures used. For non-spherical particles, and especially forelongated or plate-like particles, results may vary considerably.8.3 Data are accumulated on a number basis, and may beprocessed in that form a
33、s well.8.4 The median diameter is taken as the diameter corre-sponding to the 50th percentile of the cumulative volumedistribution. This can be determined manually by drawing aline connecting the incremental segments corresponding toeach data storage channel as shown in the sample curve in Fig.1. A
34、perpendicular is then dropped to the X-axis scale from theintersection of the drawn line and the 50th percentile grid line.9. Precision and Bias39.1 PrecisionBased on the results of a multilaboratorystudy and using the procedures and definitions of PracticeE 177 and Practice E 691 the single-laborat
35、ory, single-dayrepeatability is 62.3 % (2S %) of the mean of the measure-ments of the volume percent median equivalent sphericaldiameter. The multilaboratory, multiday reproducibility is64.6 % (2S %) of the mean of the measurements of thevolume percent median equivalent spherical diameter, when acom
36、mon calibration standard is used.5Calibration spheres or equivalent calibration materials are generally availablefrom respective instrument manufacturers.D 4438 85 (2007)29.2 BiasReference standards have not yet been certified todetermine the bias of this test method.10. Keywords10.1 catalyst; elect
37、roconductive sensing; particle sizeASTM International takes no position 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 risk
38、of infringement of such rights, are entirely their own responsibility.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
39、 standard or for additional standardsand should be addressed to ASTM 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 y
40、our views known to the ASTM Committee on Standards, at the address 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), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 1 Median Diameter-Sample CurveD 4438 85 (2007)3
