ASTM D4824-13
(Test Method)Standard Test Method for Determination of Catalyst Acidity by Ammonia Chemisorption
Standard Test Method for Determination of Catalyst Acidity by Ammonia Chemisorption
SIGNIFICANCE AND USE
5.1 This test method can be used to determine the acidity of catalysts and catalyst carriers by ammonia chemisorption for materials specifications, manufacturing control, and research and development in the evaluation of catalysts.
SCOPE
1.1 This test method covers the determination of acidity of catalysts and catalyst carriers by ammonia chemisorption. A volumetric measuring system is used to obtain the amount of chemisorbed ammonia.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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.
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Designation: D4824 − 13
Standard Test Method for
Determination of Catalyst Acidity by Ammonia
1
Chemisorption
This standard is issued under the fixed designation D4824; 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.
INTRODUCTION
This test method involves the measurement of total catalyst acidity by chemisorption of ammonia
in a static volumetric system.Acidity is a very important property in determining catalyst activity and
selectivity in many commercial reactions. Zeolite based catalysts used in the petroleum industry for
catalytic cracking are a prime example. This test method describes a simple procedure employing
inexpensive equipment that could readily be assembled in most laboratories.
1. Scope
3
V = calibrated expansion volume, cm .
1.1 This test method covers the determination of acidity of k
T = temperature of V at initial ammonia pressure, K.
catalysts and catalyst carriers by ammonia chemisorption. A 1 k
T = temperature of V at final ammonia pressure, K.
2 k
volumetric measuring system is used to obtain the amount of
P = initial ammonia pressure, torr.
1
chemisorbed ammonia.
P = final ammonia pressure, torr.
2
1.2 The values stated in SI units are to be regarded as the
W = mass of sample, g.
s
standard. The values given in parentheses are for information
W = tare of sample tube, g.
1
only.
W = sample mass plus tare of tube, g.
2
P = initial ammonia pressure corrected to standard
1T
1.3 This standard does not purport to address all of the
temperature, torr.
safety concerns, if any, associated with its use. It is the
P = final ammonia pressure corrected to standard
2T
responsibility of the user of this standard to establish appro-
temperature, torr.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Summary of Test Method
2. Referenced Documents
4.1 Asample is degassed by heating in a vacuum to remove
2
adsorbed vapors from the surface. The sample is then exposed
2.1 ASTM Standards:
to an excess of gaseous ammonia and the excess ammonia is
D3766Terminology Relating to Catalysts and Catalysis
removed by freezing it into a trap cooled with liquid nitrogen.
E691Practice for Conducting an Interlaboratory Study to
The chemisorbed ammonia is calculated as the difference
Determine the Precision of a Test Method
between the volume of ammonia before exposure and the
volume recovered in the liquid nitrogen trap.
3. Terminology
3.1 Definitions—See Terminology D3766.
5. Significance and Use
3.2 Symbols:
5.1 This test method can be used to determine the acidity of
catalysts and catalyst carriers by ammonia chemisorption for
materials specifications, manufacturing control, and research
1
This test method is under the jurisdiction of ASTM Committee D32 on
and development in the evaluation of catalysts.
Catalysts and is the direct responsibility of Subcommittee D32.01 on Physical-
Chemical Properties.
Current edition approved April 1, 2013. Published August 2013. Originally
6. Apparatus
approved in 1988. Last previous edition approved in 2008 as D4824 –03(2008).
DOI: 10.1520/D4824-13.
6.1 Aschematic diagram of one type of apparatus is shown
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
in Fig. 1. It may be constructed of glass or metal and may
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
operate manually or automatically. It has the following fea-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tures:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D4824 − 13
FIG. 1 Apparatus
6.1.1 Vacuum System, capable of attaining and maintaining 7.3 Nitrogen Gas, at least 99.9% pure, passed through
−4
pressures below 10 torr (0.01 Pa) in the absence of catalyst. drying tube.
6.1.2 Expansion Vessel, having a volume between 300 to
3 3
500 cm (V ) known to the nearest 0.01 cm (Note 1). This 8. Procedure
k
volume is defined as the volume between stopcocks V and V
7 8
8.1 Weigh sample tubes to 0.1 mg and record as W . Place
1
and includes the pressure gage and ammonia bulb.
approximately2gof sample into the sample tube.
NOTE 1—An expansion vessel of smaller volume is recommended for
8.2 Attach the sample tube to the apparatus.
materials of low surface area or smaller sample size.
8.3 Open the sample valves (V or V , or both).
6.1.3 Pressure Sensing Device or Pressure Transducer,
5 6
−1
capable of measuring 0 to 250 torr to the nearest 10 to
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4824 − 03 (Reapproved 2008) D4824 − 13
Standard Test Method for
Determination of Catalyst Acidity by Ammonia
1
Chemisorption
This standard is issued under the fixed designation D4824; 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.
INTRODUCTION
This test method involves the measurement of total catalyst acidity by chemisorption of ammonia
in a static volumetric system. Acidity is a very important parameterproperty in determining catalyst
activity and selectivity in many commercial reactions. Zeolite based catalysts used in the petroleum
industry for catalytic cracking are a prime example. This test method describes a simple procedure
employing inexpensive equipment that could readily be assembled in most laboratories.
1. Scope
1.1 This test method covers the determination of acidity of catalysts and catalyst carriers by ammonia chemisorption. A
volumetric measuring system is used to obtain the amount of chemisorbed ammonia.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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.
2. Referenced Documents
2
2.1 ASTM Standards:
D3766 Terminology Relating to Catalysts and Catalysis
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions—See Terminology D3766.
3.2 Symbols:
3
V = calibrated expansion volume, cm .
k
T = temperature of V at initial ammonia pressure, K.
1 k
T = temperature of V at final ammonia pressure, K.
2 k
P = initial ammonia pressure, torr.
1
P = final ammonia pressure, torr.
2
W = mass of sample, g.
s
W = tare of sample tube, g.
1
W = sample mass plus tare of tube, g.
2
P = initial ammonia pressure corrected to standard temperature, torr.
1T
P = final ammonia pressure corrected to standard temperature, torr.
2T
1
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.
Current edition approved April 1, 2008April 1, 2013. Published April 2008August 2013. Originally approved in 1988. Last previous edition approved in 20032008 as
D4824–03. – 03(2008). DOI: 10.1520/D4824-03R08.10.1520/D4824-13.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D4824 − 13
4. Summary of Test Method
4.1 A sample is degassed by heating in a vacuum to remove adsorbed vapors from the surface. The sample is then exposed to
an excess of gaseous ammonia and the excess ammonia is removed by freezing it into a trap cooled with liquid nitrogen. The
chemisorbed ammonia is calculated as the difference between the volume of ammonia before exposure and the volume recovered
in the liquid nitrogen trap.
5. Significance and Use
5.1 This test method can be used to determine the acidity of catalysts and catalyst carriers by ammonia chemisorption for
materials specifications, manufacturing control, and research and development in the evaluation of catalysts.
6. Apparatus
6.1 A schematic diagram of one type of apparatus is shown in Fig. 1. It may be constructed of glass or metal and may operate
manually or automatically. It has the following features:
−4
6.1.1 Vacuum System, capable of attaining and maintaining pressures below 10 torr (0.01 Pa) in the absence of catalyst.
3 3
6.1.2 Expansion Vessel, having a volume between 300 to 500 cm (V ) known to the nearest 0.01 cm (Note 1). This volume
k
is defined as the volume between stopcocks V and V and includes the pressure gage and ammonia bulb.
7 8
NOTE 1—An expansion vessel of smaller volume is recommended for materials of low surface area or smaller sample size.
6.1.3 Constant Volume Gage, Pressure Sens
...
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