ASTM D3908-03

Standard Test Method for Hydrogen Chemisorption on Supported Platinum on Alumina Catalysts and Catalyst Carriers By Volumetric Vacuum Method

SIGNIFICANCE AND USE
This test method sets forth a procedure by which duplicate catalyst samples can be compared either on an interlaboratory or intralaboratory basis. It is anticipated that catalyst producers and users will find this test method of value.
Discrimination of the samples for which this procedure is recommended must be exercised when considering carrier (support) materials that sorb appreciable quantities of hydrogen or could cause an alteration of the state of the catalyst during pretreatment, or both, (that is, sintering or metal occlusion). These materials must be identified by the user and experimented with to determine the most significant conditions of measurement.
This test method provides a measure of the total hydrogen uptake (volume of hydrogen at STP, cm3/g of catalyst) without specifying the nature of the hydrogen-platinum interaction. Persons interested in using hydrogen uptake data to calculate percent platinum dispersion in a specific catalyst should be aware of carrier (support) interactions, spill-over effects, and other phenomena related to the hydrogen uptake capabilities of the catalyst in question.
SCOPE
1.1 This test method covers the determination of the chemisorption of hydrogen at 298 K (25°C) on supported platinum catalysts that have been reduced in flowing hydrogen at 723 K (450°C). It incorporates a static volumetric vacuum technique at constant volume.
1.2 The test method is intended for use on unused supported platinum on alumina catalysts of loadings greater than 0.3 weight %. Data on other supports and lower platinum loadings were not tested.
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Sep-2003
• Technical Committee: D32 - Catalysts
• Drafting Committee: D32.01 - Physical-Chemical Properties

Relations

• Replaces: ASTM D3908-99 - Standard Test Method for Hydrogen Chemisorption on Supported Platinum on Alumina Catalysts and Catalyst Carriers By Volumetric Vacuum Method
• Effective Date: 01-Oct-2003
• Replaced By: ASTM D3908-03(2008) - Standard Test Method for Hydrogen Chemisorption on Supported Platinum Catalysts by Volumetric Vacuum Method
• Effective Date: 01-Apr-2008

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:D3908–03
Standard Test Method for
Hydrogen Chemisorption on Supported Platinum Catalysts
1
by Volumetric Vacuum Method
This standard is issued under the fixed designation D3908; 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 3.4 Symbols—The following symbols are used:
1.1 This test method covers the determination of the chemi-
sorption of hydrogen at 298 K (25°C) on supported platinum
P = pressure of gas in calibrated bulb, torr
c
catalysts that have been reduced in flowing hydrogen at 723 K
P = pressure of gas in calibrated bulb and
mc
(450°C). It incorporates a static volumetric vacuum technique
manifold, torr
at constant volume.
P = pressure in manifold, torr
m
1.2 Thetestmethodisintendedforuseonunusedsupported
P = pressure in manifold and dead space, torr
md
platinum on alumina catalysts of loadings greater than 0.3
P = pressureinmanifoldpriortoexpansioninto
m
x
weight %. Data on other supports and lower platinum loadings
sample tube for X equilibration point, torr
were not tested.
P = equilibrium pressure after expansion for
e
x
1.3 This standard does not purport to address all of the generating X equilibrium point, torr
3
safety concerns, if any, associated with its use. It is the V = volume of calibrated bulb, cm
c
V = volume of manifold between stopcocks 12
responsibility of the user of this standard to establish appro-
m
3
and 2 with only 4 and 1 open, cm
priate safety and health practices and determine the applica-
V = volume of dead space in sample cell con-
bility of regulatory limitations prior to use. d
taining catalyst (volume between 2 and 3),
3
2. Referenced Documents
cm
3
2
V (STP) = volume of gas adsorbed at STP, cm
2.1 ASTM Standards: ads x
V (STP) = cumulative volume of gas adsorbed
D3766 Terminology Relating to Catalysts and Catalysis ads cx
3
through X,cm
E177 Practice for Use of the Terms Precision and Bias in
V = monolayer volume of gas adsorbed at STP,
S
ASTM Test Methods
3
cm
E456 Terminology Relating to Quality and Statistics
T = temperature representative of the manifold
m
Ax
E691 Practice for Conducting an Interlaboratory Study to
prior to expansion into the sample cell, K
Determine the Precision of a Test Method
T = temperaturerepresentativeoftheentiresys-
m
Bx
tem after equilibrium pressure (P ) has
3. Terminology
e
x
been established, K
3.1 Definitions—See Terminology D3766.
T = temperature of manifold prior to expansion
m
3.2 Quality and Statistics—See Terminology E456.
into sample cell for dead space determina-
3.3 Precision and Bias—See Practice E177.
tion, K
T = temperature of entire system after equilib-
m
D
riumpressurehasbeenestablishedfordead
1
This test method is under the jurisdiction of ASTM Committee D32 on
space determination, K
Catalysts and is the direct responsibility of Subcommittee D32.01 on Physical-
T = average manifold temperature for a given
Chemical Properties.
dose, K
Current edition approved Oct. 1, 2003. Published October 2003. Originally
=(T + T )/2
approved in 1980. Last previous edition approved in 1999 as D3908–99.
m m
Ax Bx
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
W = mass of catalyst, g
cat
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
X = weight percent of platinum
Standards volume information, refer to the standard’s Document Summary page on
%D = percent platinum atoms on the surface
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

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D3908–03
FIG. 1 Schematic: Static Vacuum System
4. Significance and Use 5.1.4 Flow-Through Cell,thatcanbeevacuatedandthatcan
be detached from the main manifold as, for example, see Fig.
4.1 This test method sets forth a procedure by which
2. This is accomplished by including a removable joint, if
duplicate catalyst samples can be compared either on an
glass,amaleconejoint,onthemanifoldendofthetube.(Other
interlaboratory or intralaboratory basis. It is anticipated that
types of joints, that is, Swagelok with TFE-fluorocarbon
catalystproducersanduserswillfindthistestmethodofvalue.
fittings, and so forth, are suitable.) Its mate is attached to the
4.2 Discrimination of the samples for which this procedure
main manifold by a glass vacuum stopcock.Astopcock is also
is recommended must be exercised when considering carrier
included on the vent side of the cell to allow for vacuum and
(support)materialsthatsorbappreciablequantitiesofhydrogen
flow-through procedures.
or could cause an alteration o
...