ASTM D4284-12(2017)e1
(Test Method)Standard Test Method for Determining Pore Volume Distribution of Catalysts and Catalyst Carriers by Mercury Intrusion Porosimetry
Standard Test Method for Determining Pore Volume Distribution of Catalysts and Catalyst Carriers by Mercury Intrusion Porosimetry
SIGNIFICANCE AND USE
5.1 This test method is intended to determine the volume distribution of pores in catalysts and catalyst carriers with respect to the apparent diameter of the entrances to the pores. In general, both the size and volume of pores in a catalyst affect its performance. Thus, the pore volume distribution is useful in understanding a catalyst's performance and in specifying a catalyst that can be expected to perform in a desired manner.
SCOPE
1.1 This test method covers the determination of the pore volume distributions of catalysts and catalyst carriers 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 μm (3 nm).
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 WARNING—Mercury has been designated by many regulatory agencies as a hazardous material that can cause central nervous system, kidney and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website—http://www.epa.gov/mercury/faq.htm—for additional information. Users should be aware that selling mercury and/or mercury containing products into your state or country may be prohibited by law.
1.4 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 information is given in Section 8.
General Information
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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.
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Designation: D4284 − 12 (Reapproved 2017)
Standard Test Method for
Determining Pore Volume Distribution of Catalysts and
Catalyst Carriers 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 (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorial corrections made throughout in February 2017.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the determination of the pore
E177Practice for Use of the Terms Precision and Bias in
volume distributions of catalysts and catalyst carriers by the
ASTM Test Methods
method of mercury intrusion porosimetry. The range of appar-
E456Terminology Relating to Quality and Statistics
ent diameters of pores for which it is applicable is fixed by the
E691Practice for Conducting an Interlaboratory Study to
operant pressure range of the testing instrument. This range is
Determine the Precision of a Test Method
typically between apparent pore entrance diameters of about
100 and 0.003 µm (3 nm).
3. Terminology
1.2 The values stated in SI units are to be regarded as
3.1 Definitions of Terms Specific to This Standard:
standard. No other units of measurement are included in this
3.1.1 apparent pore diameter—the diameter of a pore,
standard.
assumed to be cylindrical, that is intruded at a pressure, P, and
1.3 WARNING—Mercury has been designated by many
is calculated with Eq 1.
regulatory agencies as a hazardous material that can cause
3.1.2 interparticle pores—those pores that occur between
central nervous system, kidney and liver damage. Mercury, or
particles when they are packed together and that are intruded
its vapor, may be hazardous to health and corrosive to
during the test.
materials.Cautionshouldbetakenwhenhandlingmercuryand
3.1.3 intraparticle pores—those pores lying within the en-
mercury containing products. See the applicable product Ma-
velopesoftheindividualcatalystparticlesandthatareintruded
terial Safety Data Sheet (MSDS) for details and EPA’s
during the test.
website—http://www.epa.gov/mercury/faq.htm—for addi-
3.1.4 intruded pore volume—the volume of mercury that is
tional information. Users should be aware that selling mercury
intruding into the pores during the test after this volume has
and/or mercury containing products into your state or country
been corrected, if necessary, per 13.3.2.
may be prohibited by law.
1.4 This standard does not purport to address all of the
4. Summary of Test Method
safety problems, if any, associated with its use. It is the
4.1 When a liquid does not wet a porous solid it will not
responsibility of the user of this standard to establish appro-
voluntarily enter the pores in the solid by capillary attraction.
priate safety and health practices and determine the applica-
The nonwetting liquid (mercury in this test method) must be
bility of regulatory limitations prior to use. Specific hazard
forced into the pores by the application of external pressure.
information is given in Section 8.
Thesizeoftheporesthatareintrudedisinverselyproportional
to the applied pressure. When a cylindrical pore model is
assumed, the relationship between pressure and size is:
This test method is under the jurisdiction of ASTM Committee D32 on
Catalysts and is the direct responsibility of Subcommittee D32.01 on Physical-
Chemical Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2017. Published February 2017. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1983. Last previous edition approved in 2012 as D4284–12. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4284-12R17E01. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4284 − 12 (2017)
24γ cos θ and are less subject to these alterations than some other
~ !
d 5 (1)
P materials. However, the possibility remains that the use of the
test method may alter the natural pore volume distribution that
where:
it seeks to measure.
d = apparent diameter of the pore being intruded,
γ = surface tension of the mercury,
7. Apparatus
θ = contact angle between the mercury and the solid, and
7.1 Mercury Intrusion Porosimeter, equipped with a sample
P = absolute pressure causing the intrusion.
holder capable of containing one or several catalyst or catalyst
4.2 The volume of the intruded pores is determined by
carrier particles. This holder is frequently called a penetrom-
measuring the volume of mercury that is forced into them at
eter. The porosimeter shall have a means of surrounding the
various pressures. The single determination of a pore size
test specimen with mercury at a low pressure, a pressure
distribution plot involves increasing the pressure, either con-
generator to cause intrusion, pressure transducers capable of
tinuously or step-wise, and recording the measured intruded
measuring the intruding pressure with an accuracy of at least
volume.
61% throughout the range of pressures over which the pores
of interest are being intruded, and a means of measuring the
5. Significance and Use
intruded mercury volumes with an accuracy of at least
5.1 This test method is intended to determine the volume 3 −3 3
61mm (610 cm ).
distribution of pores in catalysts and catalyst carriers with
7.2 Vacuum Pump,ifnotpartoftheporosimeter,toevacuate
respect to the apparent diameter of the entrances to the pores.
the sample holder.
Ingeneral,boththesizeandvolumeofporesinacatalystaffect
itsperformance.Thus,theporevolumedistributionisusefulin
7.3 Analytical Balance capable of measuring the sample’s
understanding a catalyst’s performance and in specifying a
mass with an accuracy of at least 60.1%. This usually means
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catalyst that can be expected to perform in a desired manner.
that the balance must be sensitive to 610 kg (60.1 mg).
7.4 Mercury, with a purity equal to, or better than, double
6. Limitations
distilled.
6.1 Mercury intrusion porosimetry, in common with many
other test methods, is only capable of sensing pores that are
8. Hazards
opentotheoutsideofacatalystorcatalystcarrierparticle,and
8.1 Samples that have been exposed to mercury are danger-
willnotdeterminethevolumeofanyporesthatarecompletely
ous. Apply the precautions that follow:
enclosed by surrounding solid.Also, the test method will only
8.1.1 Mercury is a hazardous substance that can cause
determinethevolumeofintrudableporesthathaveanapparent
illness and death. Mercury can also be absorbed through the
diameter corresponding to a pressure within the pressuring
skin; avoid direct contact.
range of the testing instrument.
8.1.2 Always store in closed containers to control its
6.2 The intrusion process proceeds from the outside of a
evaporation, and use it only in well-ventilated rooms.
particle toward its center. Comparatively large, interior pores
8.1.3 Washhandsimmediatelyafteranyoperationinvolving
can exist that have smaller pores as the only means of access.
mercury.
The test method will incorrectly register the entire volume of
8.1.4 Exerciseextremecaretoavoidspillingmercury.Clean
these “ink-bottle” pores as having the apparent diameter of the
up any spills immediately using procedures recommended
smaller access pores.
explicitly for mercury.
8.1.5 Recyclingofwastemercuryisrecommendedandtobe
6.3 Inthepenetrometer,interparticleporescanbecreatedin
conducted in accordance with local government hazardous
addition to the intraparticle pores. (See Section 3 for terminol-
waste regulations. Disposal of waste mercury and mercury-
ogy.) These interparticle pores will vary in size and volume
contaminated materials should be performed as mandated by
dependingonthesizeandshapeofthecatalystparticlesandon
local government hazardous waste regulations.
themannerinwhichtheparticlesarepackedtogetherinthetest
chamber. It is possible that some of the interparticle pores will
9. Sampling
have the same apparent diameter as some of the intraparticle
pores. When this occurs, the test method cannot distinguish
9.1 Thesamplefromwhichtestmaterialwillbedrawnshall
betweenthem.Thus,thetestmethodcanyieldanintrudedpore
be representative of the catalyst or the catalyst carrier. The
volumedistributionthatis,inpart,dependentuponthepacking
actual amount of sample used in a test will depend on the
of multi-particle samples. However, many catalysts have intra-
sensitivity of the porosimeter and the porosity of the sample.
particle pores that are much smaller than the interparticle
pores. This situation leads to a bimodal pore size distribution 10. Conditioning
and the distinction between the two classes of pores can
10.1 The ideal preconditioning for the test specimen is an
frequently be made.
outgassing procedure that removes all foreign substances from
6.4 Mercury intrusion can involve the application of high the pores and pore walls of the catalyst, but does not alter the
pressures on the sample. This may result in a temporary, or solid catalyst in any way. If possible, the appropriate combi-
permanent,alterationintheporegeometry.Generally,catalysts nation of heat and vacuum and the required time of condition-
andcatalystcarriersaremadefromcomparativelystrongsolids ingshallbeexperimentallydeterminedforthespecificcatalyst
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D4284 − 12 (2017)
directing the test, or left to the judgement of the operator.Aminimum of
or catalyst carrier under test. This outgassing technique shall
10 to 15 data points will be required to define the pore volume
then be the one specified and used.
distribution. Frequently, 25 or more points are found to be helpful. In
10.2 Where the procedure described in 10.1 is not practical,
selectingthesepressurepoints,aroughideaoftheexpecteddistributionis
helpful,sincethepressureintervalscanbelargerinregionswherelittleor
outgasthesampleinavacuumofatleast1.3Pa(10µmHg)at
no intrusion occurs. The intervals should be smaller in regions where a
a temperature of 150°C for at least 8 h.
large volume of intrusion occurs abruptly.
NOTE8—Itisnotnecessarytocontinuetheprocessuptothemaximum
NOTE1—Theprocedurein10.2isunlikelytoaltertheporestructureof
pressuring capability of the instrument if all of the pores of interest in a
a catalyst but it can severely change the pore structure of many other
particular test have been intruded at a lesser pressure.
materials.
11.8 Upon completion of the pressuring cycle, reduce the
11. Procedure
pressure and disassemble and clean the instrument in accor-
11.1 Outgasthetestsampleinaccordancewith10.1or10.2.
dance with the manufacturer’s instructions.
11.2 Weigh the outgassed specimen and record this weight.
12. Blank Test for Corrections
11.3 Place the outgassed catalyst in the penetrometer in
12.1 An intrusion test on a nonporous sample may be
accordance with the manufacturer’s instructions.
required to obtain values to use in correcting intrusion data for
NOTE 2—Since, when performing the operations described in 11.2 and
compressibilities and temperature changes.
11.3, the outgassed catalyst is exposed to the laboratory atmosphere and
12.2 Select a nonporous material for this test that has
can readsorb vapors, carry these operations out as rapidly as possible.
approximately the same compressibility and bulk volume as
11.4 Place the penetrometer containing the sample in the
the catalyst or catalyst carrier sample that is to be tested.
appropriate chamber of the porosimeter, following the manu-
facturer’s instructions, and evacuate to a pressure of at least 12.3 Test the nonporous sample in exactly the same manner
1.3Pa (10 µm Hg).
as outlined in Section 11. Raise the pressure in the same
manner as used for the catalyst tests to ensure that temperature
11.5 Fillthepenetrometerwithmercury,inaccordancewith
changes due to pressuring are the same.
themanufacturer’sinstructions,bypressuringtosomesuitably
low pressure. 12.4 The results of this blank test are a series of measured
volume changes that can also be expected to occur, along with
NOTE3—Thepressurerequiredtofillthepenetrometerwithmercuryis
actual pore intrusion, during a test on a catalyst or catalyst
also capable of filling sufficiently large pores of both the inter- and
carrier. They are used to correct the intruded volumes as
intra-particle classes. Thus, the filling process can fill some pores with
mercury and the volume distribution of these pores cannot subsequently
discussed in 13.3.2.
be determined.This fact should be recognized and, where possible, select
12.5 Thecompressibilitiesofthevariouscomponentsinthe
a filling pressure that will not intrude pores in the diameter range of
subsequent interest. system augment the measured intrusion values while the
pressure-induced heating and consequent expansion of the
11.6 Place the filled penetrometer in the pressure vessel of
system reduces the measured volumes. In a particular
the porosimeter and prepare the instrument for pressurization
instrument, either one of these effects may be dominant.
and intrusion readings in accordance with the manufacturer’s
Hence, the results of the blank test may be either an apparent
instructions.
intrusion (compressibility dominant) or an expulsion of mer-
11.7 Raise the pressure, either continuously or step-wise,
cury (heating dominant).
and record both the absolute pressure and the volume of
12.5.1 If the blank results show apparent intrusion, they are
intruded mercury until the maximum pressure of interest is
to be subtracted from the values measured in the test on the
reached.
catalyst.
NOTE 4—When raising the pressure incrementally, minimize the 12.5.2 If the blank results show a mercury expulsion, they
pressure drop during the pause. Certain modern instruments allow for an
are to be added to the volumes measured on the catalyst or
automatic repressurization to the target pressure when the pressure
catalyst carrier.
decreases.When samples with relatively narrow pore size distribution are
analyzed, the extent of depressurization and repressurization may affect
13. Calculations
test method precision and the measured pore volume.
NOTE 5—When testing some materials, the time required to achieve
13.1 Express the intruding pressures as absolute pressures
intrusion equilibrium will not be the same at all pressures. Often, the
pri
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