ASTM D4464-15(2020)
(Test Method)Standard Test Method for Particle Size Distribution of Catalytic Materials by Laser Light Scattering
Standard Test Method for Particle Size Distribution of Catalytic Materials by Laser Light Scattering
SIGNIFICANCE AND USE
5.1 It is important to recognize that the results obtained by this test method or any other method for particle size determination utilizing different physical principles may disagree. The results are strongly influenced by physical principles employed by each method of particle size analysis. The results of any particle sizing method should be used only in a relative sense and should not be regarded as absolute when comparing results obtained by other methods. Particularly for fine materials (that is, average particle size 3
5.2 Light scattering theories (Fraunhofer Diffraction4 and Mie Scattering5) that are used for determination of particle size have been available for many years. Several manufacturers of testing equipment now have units based on these principles. Although each type of testing equipment utilizes the same basic principles for light scattering as a function of particle size, different assumptions pertinent to application of the theory and different models for converting light measurements to particle size, may lead to different results for each instrument. Furthermore, any particles which are outside the size measurement range of the instrument will be ignored, causing an increase in the reported percentages within the detectable range. A particle size distribution which ends abruptly at the detection limit of the instrument may indicate that particles outside the range are present. Therefore, use of this test method cannot guarantee directly comparable results from different types of instruments.
5.3 This test method can be used to determine particle size distributions of catalysts, supports, and catalytic raw materials for specifications, manufacturing control, and research and development work.
5.4 For fine materials (that is, average particle size 6
SCOPE
1.1 This test method covers the determination of the particle size distribution of catalyst, catalyst carrier, and catalytic raw material particles and is one of several found valuable for the measurement of particle size. The range of average particle sizes investigated was from 1 to 300 μm equivalent spherical diameter. The technique is capable of measuring particles above and below this range. The angle and intensity of laser light scattered by the particles are selectively measured to permit calculation of a volume distribution using light-scattering techniques.
1.2 The values stated in SI units are to be regarded as standard. 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 responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4464 − 15 (Reapproved 2020)
Standard Test Method for
Particle Size Distribution of Catalytic Materials by Laser
Light Scattering
This standard is issued under the fixed designation D4464; 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 E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1.1 Thistestmethodcoversthedeterminationoftheparticle
E456 Terminology Relating to Quality and Statistics
size distribution of catalyst, catalyst carrier, and catalytic raw
E691 Practice for Conducting an Interlaboratory Study to
material particles and is one of several found valuable for the
Determine the Precision of a Test Method
measurement of particle size. The range of average particle
E1617 Practice for Reporting Particle Size Characterization
sizes investigated was from 1 to 300 µm equivalent spherical
Data
diameter. The technique is capable of measuring particles
above and below this range. The angle and intensity of laser
3. Terminology
light scattered by the particles are selectively measured to
3.1 Definitions and recommended nomenclature pertaining
permit calculation of a volume distribution using light-
to catalysts and to materials used in their manufacture can be
scattering techniques.
found in Terminology D3766.
1.2 The values stated in SI units are to be regarded as
3.2 Definitions of Terms Specific to This Standard:
standard. No other units of measurement are included in this
3.2.1 background—extraneous scattering of light by mate-
standard.
rial present in the dispersion fluid other than the particles to be
1.3 This standard does not purport to address all of the
measured. It includes scattering by contamination in the
safety concerns, if any, associated with its use. It is the
measurement path.
responsibility of the user of this standard to establish appro-
3.2.2 Fraunhofer Diffraction—the optical theory that de-
priate safety, health, and environmental practices and deter-
scribes the low-angle scattering of light by particles that are
mine the applicability of regulatory limitations prior to use.
large compared to the wavelength of the incident light.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard- 3.2.3 Mie Scattering—the complex electromagnetic theory
that describes the scattering of light by spherical particles. It is
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- applied when the sample includes particles with diameters that
are close to the wavelength of the incident light. The real and
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. imaginaryindicesoflightrefractionoftheparticlesareneeded.
3.2.4 multiple scattering—the re-scattering of light by a
2. Referenced Documents
particle in the path of light scattered by another particle. This
usually occurs in heavy concentrations of a particle dispersion.
2.1 ASTM Standards:
D3766 Terminology Relating to Catalysts and Catalysis
4. Summary of Test Method
E105 Practice for Probability Sampling of Materials
4.1 Aprepared sample of particulate material is dispersed in
water or a compatible organic liquid and is circulated through
This test method is under the jurisdiction of ASTM Committee D32 on the path of a laser light beam or some other suitable source of
Catalysts and is the direct responsibility of Subcommittee D32.02 on Physical-
light. The particles pass through the light beam and scatter it.
Mechanical Properties.
Photodetector arrays collect the scattered light which is con-
Current edition approved May 15, 2020. Published June 2020. Originally
verted to electrical signals to be analyzed using Fraunhofer
approved in 1985. Last previous edition approved in 2015 as D4464 – 15. DOI:
10.1520/D4464-15R20.
Diffraction, or Mie Scattering, or both. Scattering information,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
typically, is analyzed assuming a spherical geometry for the
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
particles. Calculated particle sizes are, therefore, presented as
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. equivalent spherical diameters.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4464 − 15 (2020)
5. Significance and Use measured at 589.3 nm (sodium light) but often values at other
wavelengths are also given. Extrapolation, interpolation, or
5.1 It is important to recognize that the results obtained by
estimation to the wavelength of the laser being used can
this test method or any other method for particle size determi-
therefore be made.
nation utilizing different physical principles may disagree. The
results are strongly influenced by physical principles employed
6. Interferences
by each method of particle size analysis. The results of any
6.1 Air bubbles entrained in the circulating fluid will scatter
particle sizing method should be used only in a relative sense
light and then be reported as particles. Circulating fluids,
andshouldnotberegardedasabsolutewhencomparingresults
typically, do not require degassing, but should be bubble-free
obtained by other methods. Particularly for fine materials (that
on visual inspections.
is, average particle size < 20 µm), significant differences are
oftenobservedforlaserlightscatteringinstrumentsofdifferent
6.2 Contaminants, such as non-aqueous solvents, oil or
manufacturers. These differences include lasers of different
other organic coatings on the sample may emulsify in an
wavelengths,detectorconfiguration,andthealgorithmsusedto
aqueous carrier, scatter light, and be reported as part of the
convert scattering to particle size distribution. Therefore,
particle size distribution. Samples containing such contami-
comparison of results from different instruments may be
nants may be analyzed in a non-aqueous carrier solvent to
misleading.
dissolve the contaminants or washed free of the contaminant
with a compatible aqueous solvent.
5.2 Light scattering theories (Fraunhofer Diffraction and
MieScattering )thatareusedfordeterminationofparticlesize
6.3 Reagglomeration or settling of particles during analysis
have been available for many years. Several manufacturers of
will cause erroneous results. Dispersions shall be prepared
testing equipment now have units based on these principles.
such that a stable dispersion is maintained throughout the
Although each type of testing equipment utilizes the same
analysis.
basic principles for light scattering as a function of particle
6.4 Insufficient sample loading may cause electrical noise
size, different assumptions pertinent to application of the
interference and poor data reproducibility. High sample load-
theory and different models for converting light measurements
ing may cause excessive light attenuation and multiple
to particle size, may lead to different results for each instru-
scattering, resulting in erroneous particle size distributions.
ment. Furthermore, any particles which are outside the size
measurement range of the instrument will be ignored, causing
7. Apparatus
an increase in the reported percentages within the detectable
7.1 Particle Size Analyzer, based on Fraunhofer Diffraction
range. A particle size distribution which ends abruptly at the
or Mie Scattering, or both, light scattering analysis techniques.
detection limit of the instrument may indicate that particles
Ensure that the analyzer system or subsystem is optimum for
outsidetherangearepresent.Therefore,useofthistestmethod
the range of the powder being tested.
cannot guarantee directly comparable results from different
types of instruments.
7.2 Micro Sample Splitter, used in accordance with
MNL 32 to obtain the test portion of sample.
5.3 This test method can be used to determine particle size
distributions of catalysts, supports, and catalytic raw materials
7.3 Ultrasonic Probe or Bath, if needed, to ensure disper-
for specifications, manufacturing control, and research and
sion of agglomerates prior to analysis.
development work.
8. Reagents and Materials
5.4 For fine materials (that is, average particle size < 20
µm), it is critical that Mie Scattering Theory be applied. This 8.1 The selected liquid carrier shall:
8.1.1 Be compatible with the construction materials of the
involves entering an “optical model” consisting of the “real”
and “imaginary” refractive indices of the solid at the wave- sample delivery system.
8.1.2 Not cause dissolution or clumping of the particles.
length of the laser. The “imaginary” refractive index is also
referred to as the “absorbance,” as it has a value of zero for 8.1.3 Besufficientlycleantoachieveacceptablebackground
levels.
transparent materials such as glass beads. For common mate-
rials and naturally occurring minerals (for example, kaolin),
8.2 The use of surfactant(s) is often recommended by
these values are known and published, and usually included in
equipmentmanufacturers.However,agentssuchassurfactants,
the manufacturer’s instrument manual (for example, as an
antifoams,andviscositymodifiersshouldbeusedwithcaution.
appendix). For example, kaolinite measured at 589.3 nm has a
An interlaboratory study of this test method showed that the
“real” refractive index of 1.55. The absorbance (imaginary
use of different types and concentrations of surfactant can
component) for minerals and metal oxides is normally taken as
significantly affect the results. In calculating the precision of
0.001, 0.01 or 0.1. Many of the published values were
this test method, results obtained using surfactants were
excluded because they contributed disproportionately to the
Jillavenkatesa, A., et al., Particle Size Characterization, NIST Recommended
Practice Guide SP 960-1, 2001.
4 6
Born, M., and Wolf, E., Principles of Optics, Chapter 8, Pergamon Press, Xu, R., Particle Characterization: Light Scattering Methods, Chapter 3,
Oxford, 1957. KluwerAcademic Publishers, 2000.
5 7
van Hulst, H. C., Light Scattering by Small Particles, Chapter 9, John Wiley & MNL 32, “ Manual on Test Sieving Methods,” Pope, L. R. and Ward, C. W.,
Sons, New York, 1908. eds., 4th ed, ASTM International, 1998 .
D4464 − 15 (2020)
NOTE 2—A duplicate run of the sample is highly recommended as this
scatter in results. Comparisons between laboratories should be
will allow detection of anomalous artifacts in any single run.
performed with liquid carriers which are identical in all
respects. 12.5 Select the desired output parameters according to the
requirements set forth by the instrument manufacturer.
9. Sampling and Sample Size
12.6 Transfer a representative aliquot to the sample delivery
9.1 Arepresentative test sample shall be obtained according
system and allow it to circulate for at least 20 s or until the
to Practice E105. The test portion shall be extracted from the
solid is uniformly dispersed before measuring.
test sample using a micro sample splitter according to
NOTE 3—Determine that the sample is not settling out in the circulation
MNL 32. Quartering shall not be used.
system. This can be checked by repeated runs at higher circulation rates.
9.2 Refer to the equipment manufacturer’s recommendation NOTE 4—Although this standard does not explicitly address the use of
dispersion agents or ultrasound as aids in dispersion, the user should be
to ensure that the amount of the test portion is acceptable to
aware that both are often necessary and utilized to ensure dispersion.
achieve optimum light scattering conditions. A wide range of
12.7 Perform the sample analysis according to the manufac-
sample portions is acceptable depending upon median particle
turer’s instructions.
size, particle density, and the sample delivery system.
12.8 Drain and fill the sample dispersion system in prepa-
9.3 For liquid dispersed materials, redisperse as necessary
ration for the next sample analysis. Drain and clean, as
to ensure representative samples.
necessary, to avoid contamination of the subsequent sample.
10. Preparation of Apparatus
12.9 Itisimportanttorepeat12.2beforetheanalysisofeach
10.1 Allow the instrument to warm up according to the
sample.
manufacturer’s recommendations.
13. Report
10.2 Install and fill the desired sample delivery system and
select applicable instrument range as indicated by the instru- 13.1 Information shall be reported as agreed between sup-
plier and user, in accordance with Practice E1617.The basis of
ment manufacturer’s instructions.
thereportedresultsispercentvolumedistributioncalculatedas
10.3 Establish correct optical alignment and calibration at a
equivalent spherical diameter. If all particles have the same
frequencyinaccordancewiththemanufacturer’srequirements.
density, this is the same as percent weight distribution.
11. Calibration and Standardization
13.2 When reporting particle size data obtained by laser
light scattering, one should ensure that the make and model of
11.1 Performance of the instrument is defined by the geom-
the instrument are indicated, together with the refractive index
etry of the optical components. (Refer to the manufacturer’s
value(s)used(thatis,the‘opticalmodel’).IfFraunhofertheory
instruction manual.)
is employed (that is, no optical model), then ‘Fraunhofer’
11.2 Spherical particle standards are available. Diagnostic
should be indicated in place of the refractive index values.
powders are available from some equipment manufacturers to
ensure consistent instrument function. (Some instruments may 10
14. Precision and Bias
permit the use of reticles for calibration.)
14.1 Test Program—The previous interlaboratory study
NOTE 1—Apartial list of standards, powders, and reticles can be found
(1995) was conducted in which particle size was measured as
in RR:D32-1013.
three points in seven separate laboratories on three materials.
Each laboratory conducted multiple determinations on each of
12. Procedure
three samples. Practice E691, modified for nonuniform data
12.1 Before analysis of each sample, ensure that the mea-
sets, was followed for the data reduction.
suring cell is clean per manufacturer’s instructions.
NOTE 5—Use of the terms repeatability, r
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