ASTM D4284-03

Standard Test Method for Determining Pore Volume Distribution of Catalysts by Mercury Intrusion Porosimetry

SCOPE
1.1 This test method covers the determination of the pore volume distributions of catalysts and catalyst supports by the method of mercury intrusion porosimetry. The range of apparent diameters of pores for which it is applicable is fixed by the operant pressure range of the testing instrument. This range is typically between apparent pore entrance diameters of about 100 and 0.003 m (3 nm).
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 8.

General Information

• Status: Historical
• Publication Date: 09-Mar-2003
• ICS: 71.040.30 - Chemical reagents
• Technical Committee: D32 - Catalysts
• Drafting Committee: D32.01 - Physical-Chemical Properties

Relations

• Replaced By: ASTM D4284-07 - Standard Test Method for Determining Pore Volume Distribution of Catalysts by Mercury Intrusion Porosimetry
• Effective Date: 01-Apr-2007
• Referred By: ASTM C1793-15 - Standard Guide for Development of Specifications for Fiber Reinforced Silicon Carbide-Silicon Carbide Composite Structures for Nuclear Applications
• Effective Date: 10-Mar-2003
• Referred By: ASTM D8413-22 - Standard Guide for Measuring the Water Pore Volume of Catalytic Materials by Centrifuge
• Effective Date: 10-Mar-2003
• Referred By: ASTM D8393-21 - Standard Guide for Determination of Pore Volume of Powdered Catalysts and Catalyst Carriers by Water Adsorption
• Effective Date: 10-Mar-2003
• Referred By: ASTM C1783-15 - Standard Guide for Development of Specifications for Fiber Reinforced Carbon-Carbon Composite Structures for Nuclear Applications
• Effective Date: 10-Mar-2003

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D4284–03
Standard Test Method for
Determining Pore Volume Distribution of Catalysts by
Mercury Intrusion Porosimetry
This standard is issued under the fixed designation D4284; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.4 intruded pore volume—the volume of mercury that is
intruding into the pores during the test after this volume has
1.1 This test method covers the determination of the pore
been corrected, if necessary, per 13.3.2.
volume distributions of catalysts and catalyst supports by the
method of mercury intrusion porosimetry. The range of appar-
4. Summary of Test Method
ent diameters of pores for which it is applicable is fixed by the
4.1 When a liquid does not wet a porous solid it will not
operant pressure range of the testing instrument. This range is
voluntarily enter the pores in the solid by capillary attraction.
typically between apparent pore entrance diameters of about
The nonwetting liquid (mercury in this test method) must be
100 and 0.003 µm (3 nm).
forced into the pores by the application of external pressure.
1.2 The values stated in SI units are to be regarded as
Thesizeoftheporesthatareintrudedisinverselyproportional
standard. The values given in parentheses are provided for
to the applied pressure. When a cylindrical pore model is
information only.
assumed, the relationship between pressure and size is:
1.3 This standard does not purport to address all of the
safety problems, if any, associated with its use. It is the 24g~cosu!
d 5 (1)
P
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
where:
bility of regulatory limitations prior to use. Specific hazard
d = apparent diameter of the pore being intruded,
statements are given in Section 8.
g = surface tension of the mercury,
u = contact angle between the mercury and the solid, and
2. Referenced Documents
P = absolute pressure causing the intrusion.
2.1 ASTM Standards:
4.2 The volume of the intruded pores is determined by
E177 Practice for Use of the Terms Precision and Bias in
measuring the volume of mercury that is forced into them at
ASTM Test Methods
variouspressures.Asingle-poresizedistributiondetermination
E456 Terminology Relating to Quality and Statistics
involves increasing the pressure, either continuously or step-
E691 Practice for Conducting an Interlaboratory Study to
wise, and recording the measured intruded volume.
Determine the Precision of a Test Method
5. Significance and Use
3. Terminology
5.1 This test method is intended to determine the volume
3.1 Definitions of Terms Specific to This Standard:
distribution of pores in catalysts with respect to the apparent
3.1.1 apparent pore diameter—the diameter of a pore,
diameteroftheentrancestothepores.Ingeneral,boththesize
assumed to be cylindrical, that is intruded at a pressure, P, and
and volume of pores in a catalyst affect its performance.Thus,
is calculated with Eq 1.
the pore volume distribution is useful in understanding a
3.1.2 interparticle pores—those pores that occur between
catalyst’s performance and in specifying a catalyst that can be
particles when they are packed together and that are intruded
expected to perform in a desired manner.
during the test.
3.1.3 intraparticle pores—those pores lying within the en-
6. Limitations
velopesoftheindividualcatalystparticlesandthatareintruded
6.1 Mercury intrusion porosimetry, in common with many
during the test.
other test methods, is only capable of sensing pores that are
opentotheoutsideofacatalystparticle,andwillnotdetermine
the volume of any pores that are completely enclosed by
This test method is under the jurisdiction of ASTM Committee D32 on
Catalysts and is the direct responsibility of Subcommittee D32.01 on Physical-
surrounding solid. Also, the test method will only determine
Chemical Properties.
the volume of intrudable pores that have an apparent diameter
Current edition approved March 10, 2003. Published April 2003. Originally
corresponding to a pressure within the pressuring range of the
approved in 1983. Discontinued April 2001 and reinstated as D4284–03.
testing instrument.
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4284–03
6.2 The intrusion process proceeds from the outside of a 9. Sampling
particle toward its center. Comparatively large, interior pores
9.1 Thesamplefromwhichtestmaterialwillbedrawnshall
can exist that have smaller pores as the only means of access.
be representative of the catalyst.The actual amount of catalyst
The test method will incorrectly register the entire volume of
used in a test will depend on the sensitivity of the porosimeter
these “ink-bottle” pores as having the apparent diameter of the
and the porosity of the sample.
smaller access pores.
6.3 Inthepenetrometer,interparticleporescanbecreatedin
10. Conditioning
addition to the intraparticle pores. (See Section 3 for terminol-
10.1 The ideal preconditioning for the test specimen is an
ogy.) These interparticle pores will vary in size and volume
outgassing procedure that removes all foreign substances from
dependingonthesizeandshapeofthecatalystparticlesandon
the pores and pore walls of the catalyst, but does not alter the
themannerinwhichtheparticlesarepackedtogetherinthetest
solid catalyst in any way. If possible, the appropriate combi-
chamber. It is possible that some of the interparticle pores will
nation of heat and vacuum and the required time of condition-
have the same apparent diameter as some of the intraparticle
ingshallbeexperimentallydeterminedforthespecificcatalyst
pores. When this occurs, the test method cannot distinguish
under test. This outgassing technique shall then be the one
betweenthem.Thus,thetestmethodcanyieldanintrudedpore
specified and used.
volumedistributionthatis,inpart,dependentuponthepacking
10.2 Where the procedure described in 10.1 is not practical,
of multi-particle samples. However, many catalysts have intra-
outgasthecatalystinavacuumofatleast1.3Pa(10µmHg)at
particle pores that are much smaller than the interparticle
a temperature of 150°C for at least 8 h.
pores. This situation leads to a bimodal pore size distribution
NOTE 1—Theprocedurein10.2isunlikelytoaltertheporestructureof
and the distinction between the two classes of pores can
a catalyst but it can severely change the pore structure of many other
frequently be made.
materials.
6.4 Mercury intrusion can involve the application of high
pressures on the sample. This may result in a temporary, or
11. Procedure
permanent,alterationintheporegeometry.Generally,catalysts
11.1 Outgasthetestsampleinaccordancewith10.1or10.2.
aremadefromcomparativelystrongsolidsandarelesssubject
11.2 Weigh the outgassed specimen and record this weight.
to these alterations than some other materials. However, the
11.3 Place the outgassed catalyst in the penetrometer in
possibilityremainsthattheuseofthetestmethodmayalterthe
accordance with the manufacturer’s instructions.
natural pore volume distribution that it seeks to measure.
NOTE 2—Since, when performing the operations described in 11.2 and
11.3, the outgassed catalyst is exposed to the laboratory atmosphere and
7. Apparatus
can readsorb vapors, carry these operations out as rapidly as possible.
7.1 Mercury Intrusion Porosimeter,equippedwithasample
11.4 Place the penetrometer containing the sample in the
holder capable of containing one or several catalyst particles.
appropriate chamber of the porosimeter, following the manu-
This holder is frequently called a penetrometer. The porosim-
facturer’sinstructions,andevacuatetoapressureofatleast1.3
eter shall have a means of surrounding the test specimen with
Pa (10 µm Hg).
mercury at a low pressure, a pressure generator to cause
11.5 Fillthepenetrometerwithmercury,inaccordancewith
intrusion, pressure transducers capable of measuring the in-
themanufacturer’sinstructions,bypressuringtosomesuitably
truding pressure with an accuracy of at least 61% throughout
low pressure.
the range of pressures over which the pores of interest are
beingintruded,andameansofmeasuringtheintrudedmercury
NOTE 3—Thepressurerequiredtofillthepenetrometerwithmercuryis
3 −3 3
volumes with an accuracy of at least 61mm (610 cm ). also capable of filling sufficiently large pores of both the inter- and
intra-particle classes. Thus, the filling process can fill some pores with
7.2 Vacuum Pump,ifnotpartoftheporosimeter,toevacuate
mercury and the volume distribution of these pores cannot subsequently
the sample holder.
be determined.This fact should be recognized and, where possible, select
7.3 Analytical Balance capable of measuring the sample’s
a filling pressure that will not intrude pores in the diameter range of
mass with an accuracy of at least 60.1%. This usually means
subsequent interest.
−7
that the balance must be sensitive to 610 kg (60.1 mg).
11.6 Place the filled penetrometer in the pressure vessel of
7.4 Mercury, with a purity equal to, or better than, double
the porosimeter and prepare the instrument for pressurization
distilled.
and intrusion readings in accordance with the manufacturer’s
instructions.
8. Hazards
11.7 Raise the pressure, either continuously or step-wise,
8.1 Samples that have been exposed to mercury are danger-
and record both the absolute pressure and the volume of
ous. (Warning—Mercury is a hazardous substance that can
intruded mercury until the maximum pressure of interest is
cause illness and death. Always store in closed containers to
reached.
control its evaporation, and use it only in well-ventilated
NOTE 4—When raising the pressure incrementally, minimize the pres-
rooms. Mercury can also be absorbed through the skin, avoid
sure drop during the pause. Certain modern instruments allow for an
direct contact. Wash hands immediately after any operation
automatic repressurization to the target pressure when the pressure
involving mercury. Exercise extreme care to avoid spilling
decreases.When samples with relatively narrow pore size distribution are
mercury. Clean up any spills immediately using procedures
analyzed, the extent of depressurization and repressurization may affect
recommended explicitly for mercury.) test method precision and the measured pore volume.
D4284–03
NOTE 5—When testing some materials, the time required to achieve
absolutepressuresinaccordancewiththeinstrumentmanufac-
intrusion equilibrium will not be the same at all pressures. Often, the
turer’s instructions. If the instrument reads directly in absolute
equilibrium time is appreciably longer at pressures that cause an abrupt
pressure, omit this step.
and large increase in intruded volume. Failure to record the equilibrium
13.2 The absolute pressures are next converted to apparent
intrusionwillresultinsomeoftheporevolumebeingincorrectlyascribed
intruded pore diameters with the equation in 4.1. This step
to smaller pore diameters. Assess the extent to which this may be a
requires that the surface tension and contact angle be known.
problem by conducting two tests, each at a different pressuring rate, and
compare the results. Measure recorded intrusion values at, essentially, 13.2.1 When double-distilled mercury is used, the value of
equilibrium.
the surface tension can generally be relied upon to be that
NOTE 6—Use of Eq 1 requires the absolute pressure, P. With some
reported in handbooks, for example, 0.484 N/m (484 d/cm) at
instruments, it may not be possible to read the absolute pressure directly.
25°C. Small deviations from this value are not significant as
In this case, record the gage pressure and calculate the absolute pressures
the surface tension enters the equation as a linear term.
subsequently.
13.2.2 The contact angle enters the equation as its cosine,
NOTE 7—If incremental pressure steps are used, the choice of pressure
and it is more important to know the value of the angle
intervals at which data are to be recorded will be specified by those
directing the test or, left to the judgement of the operator.Aminimum of
accurately for the material under test. The contact angle of
10 to 15 data points will be required to define the pore volume
mercury has been measured on a variety of solids by several
distribution. Frequently, 25 or more points are found to be helpful. In
different techniques, and references to some of these measure-
selectingthesepressurepoints,aroughideaoftheexpecteddistributionis
mentsaregiveninAppendixX1whichalsolistsreferencesfor
helpful,sincethepressureintervalscanbelargerinregionswherelittleor
several methods of contact angle measurement that have been
no intrusion occurs. The intervals should be smaller in regions where a
founduseful(1-6). Theidealvalueforreducingthedataisone
large volume of intrusion occurs abruptly.
that has been determined for the particular material under test.
NOTE 8—Itisnotnecessarytocontinuetheprocessuptothemaximum
pressuring capability of the instrument if all of the pores of interest in a
If this is impractical, the use of an assumed value is necessary.
particular test have been intruded at a lesser pressure.
Ifmercuryintrusionisbeingusedforthecomparisonofsimilar
materials for quality control purposes, then an assumed, or
11.8 Upon completion of the pressuring cycle, reduce the
agreed upon, value is satisfactory. But, when different materi-
pressure and disassemble and clean the instrument in accor-
alsarebeingcompared,theassumptionofasinglevalueforthe
dance with the manufacturer’s instructions.
contact angle can lead to errors.
12. Blank Test for Corrections
13.3 Thenextstepinthecalculationsisthecorrectionofthe
12.1 An intrusion test on a nonporous sample may be intruded volume readings. The corrections fall into two cat-
required to obtain values to use in correcting intrusion data for
egories: low-pressure corrections and high-pressure correc-
compressibilities and temperature changes. tions.
12.2 Select a nonporous material for this test that has
13.3.1 A low-pressure correction, that accounts for the
approximately the same compressibility and bulk volume as compression of air trapped during filling, can be applied as
the catalyst sample that is to be tested.
discussed in Ref (4). However, this correction should not be
12.3 Test the nonporous sample in exactly the same manner necessary if mercury filling is carried out as required in 11.4.
as outlined in Section 11. Raise the pressure in
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