ASTM D3943-21

Standard Test Method for Total Molybdenum in Fresh Alumina-Base Catalysts

SIGNIFICANCE AND USE
4.1 This test method sets forth a procedure by which catalyst samples can be compared either on an interlaboratory or intralaboratory basis. It is anticipated that catalyst producers and users will find this method of value.
SCOPE
1.1 This test method covers the determination of molybdenum in alumina-base catalysts and has been cooperatively tested at molybdenum concentrations from 8 to 18 weight %, expressed as MoO3. Any component of the catalyst other than molybdenum such as iron, tungsten, etc., which is capable of being oxidized by either ferric or ceric ions after being passed through a zinc-amalgam reductor column (Jones reductor) will interfere.  
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 Many catalysts that contain molybdenum also contain other metals, nickel for example, that may be regulated by the EPA. Go to the material safety data sheet for the catalyst material being analyzed. More information can be found at EPA.gov. Additional information on nickel containing catalysts can be found in Test Method D4481.  
1.4 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.  
1.5 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

• Status: Published
• Publication Date: 31-May-2021
• ICS: 71.040.30 - Chemical reagents
• Technical Committee: D32 - Catalysts
• Drafting Committee: D32.03 - Chemical Composition

Relations

• Refers: ASTM D4481-10 - Standard Test Method for Total Nickel in Fresh Alumina-Base Catalysts
• Effective Date: 01-Apr-2010
• Refers: ASTM E507-09 - Standard Test Method for Determination of Aluminum in Iron Ores by Flame Atomic Absorption Spectrometry
• Effective Date: 01-Oct-2009
• Refers: ASTM E507-08 - Standard Test Method for Analysis of Aluminum in Iron Ores by Flame Atomic Absorption Spectrometry
• Effective Date: 01-Nov-2008
• Refers: ASTM D7442-08a - Standard Practice for Sample Preparation of Fluid Catalytic Cracking Catalysts and Zeolites for Elemental Analysis by Inductively Coupled Plasma Atomic Emission Spectroscopy
• Effective Date: 01-Sep-2008
• Refers: ASTM D7442-08 - Standard Practice for Sample Preparation of Fluid Catalytic Cracking Catalysts and Zeolites for Elemental Analysis by Inductively Coupled Plasma Atomic Emission Spectroscopy
• Effective Date: 01-Apr-2008
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D4481-04 - Standard Test Method for Total Nickel in Fresh Alumina-Base Catalysts
• Effective Date: 01-Apr-2004
• Refers: ASTM E507-03 - Standard Test Method for Aluminum in Iron Ores by Atomic Absorption Spectrometry
• Effective Date: 10-Jun-2003
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM E507-98 - Standard Test Method for Aluminum in Iron Ores by Atomic Absorption Spectrometry
• Effective Date: 10-May-1998
• Refers: ASTM D4481-97 - Standard Test Method for Total Nickel in Fresh Alumina-Base Catalysts
• Effective Date: 01-Jan-1997

Overview

ASTM D3943-21, titled Standard Test Method for Total Molybdenum in Fresh Alumina-Base Catalysts, establishes a procedure for determining the total molybdenum content in alumina-based catalysts. Developed by ASTM International, this standard enables catalyst producers and users to compare molybdenum levels within and between laboratories, promoting consistency and reliability in catalyst quality assessment. The test method is based on the analysis of samples with molybdenum concentrations ranging from 8 to 18 weight percent, expressed as molybdenum trioxide (MoO₃).

Key Topics

• Molybdenum Determination: The standard outlines a wet chemical analysis technique utilizing sulfuric acid digestion, reduction in a Jones reductor column, and subsequent titration with standardized ceric sulfate solution. This process specifically quantifies molybdenum content as MoO₃.
• Interference Considerations: Elements such as iron, tungsten, arsenic, antimony, chromium, titanium, vanadium, and uranium may interfere if they are oxidized under the test conditions. Proper sample preparation and checking for interferences are essential.
• Safety and Compliance: Laboratories are reminded to consult material safety data sheets for catalyst materials, especially when dealing with catalysts that may contain regulated metals like nickel. Users should adhere to appropriate safety, health, and environmental practices, and consider any regulatory limitations.
• Standardized Units: The method employs SI units for all measurements to ensure international consistency.

Applications

ASTM D3943-21 is primarily used in industries where alumina-base catalysts are manufactured or utilized, including:

• Catalyst Quality Control: Producers can verify the molybdenum content in new batches, ensuring product specifications and performance criteria are met.
• Comparison Between Laboratories: The standardized procedure allows for reliable data comparison both internally and across different sites or organizations.
• Regulatory Compliance: Knowing the precise molybdenum content helps users and producers respond to environmental or product regulations, particularly where catalysts may include additional elements like nickel, which are subject to government oversight.
• R&D and Process Optimization: Research and development teams use this method to evaluate and optimize catalyst formulations for industrial processes.

Related Standards

For comprehensive catalyst characterization and analysis, users of ASTM D3943-21 may also refer to the following standards:

• ASTM D1193 - Specification for Reagent Water: Addresses water quality used in analytical chemistry methods.
• ASTM D4481 - Test Method for Total Nickel in Fresh Alumina-Base Catalysts: Provides procedures for nickel content analysis, essential for catalysts containing nickel.
• ASTM D7442 - Practice for Sample Preparation of Fluid Catalytic Cracking Catalysts and Zeolites for Elemental Analysis by Inductively Coupled Plasma Optical Emission Spectroscopy.
• ASTM E507 - Test Method for Determination of Aluminum in Iron Ores by Flame Atomic Absorption Spectrometry (withdrawn but relevant for reference).
• Additional resources and regulatory information related to metallic catalyst components can be found at EPA.gov.

Practical Value

ASTM D3943-21 ensures the accurate quantification of total molybdenum in alumina-based catalysts, which is critical to catalyst performance in various chemical processes. By adhering to this standard, organizations improve product consistency, facilitate compliance with quality and environmental standards, and enhance communication and trust across supply chains. This test method supports robust quality assurance for catalyst manufacturers, chemical processors, and regulatory agencies alike.

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: D3943 − 21
Standard Test Method for
Total Molybdenum in Fresh Alumina-Base Catalysts
This standard is issued under the fixed designation D3943; 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 D4481 Test Method for Total Nickel in FreshAlumina-Base
Catalysts
1.1 This test method covers the determination of molybde-
D7442 Practice for Sample Preparation of Fluid Catalytic
num in alumina-base catalysts and has been cooperatively
CrackingCatalystsandZeolitesforElementalAnalysisby
tested at molybdenum concentrations from 8 to 18 weight %,
Inductively Coupled Plasma Optical Emission Spectros-
expressed as MoO . Any component of the catalyst other than
copy
molybdenum such as iron, tungsten, etc., which is capable of
E173 Practice for Conducting Interlaboratory Studies of
being oxidized by either ferric or ceric ions after being passed
Methods for Chemical Analysis of Metals (Withdrawn
through a zinc-amalgam reductor column (Jones reductor) will
1998)
interfere.
E507 Test Method for Determination of Aluminum in Iron
1.2 Units—The values stated in SI units are to be regarded
Ores by Flame Atomic Absorption Spectrometry
as standard. No other units of measurement are included in this
standard.
3. Summary of Test Method
1.3 Many catalysts that contain molybdenum also contain
3.1 The catalyst is digested in hot sulfuric acid to dissolve
other metals, nickel for example, that may be regulated by the
molybdenum, destroy organic matter, and to expel nitrates if
EPA. Go to the material safety data sheet for the catalyst
present. The acid solution is diluted and passed through an
material being analyzed. More information can be found at
amalgamated zinc column (Jones reductor) into a receiving
EPA.gov.Additionalinformationonnickelcontainingcatalysts
flask containing an excess of ferric ammonium sulfate. The
+6
can be found in Test Method D4481.
column quantitatively reduces the molybdenum (Mo to
+3
Mo ) which in turn is reoxidized in the receiving flask
1.4 This standard does not purport to address all of the
according to the reaction:
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 13 13 16 12
Mo 13Fe →Mo 13Fe (1)
priate safety, health, and environmental practices and deter-
+3
3.2 The ferrous ion produced (three per Mo oxidized) is
mine the applicability of regulatory limitations prior to use.
titrated with standard ceric sulfate solution in the presence of
1.5 This international standard was developed in accor-
ferroin indicator. The indicator undergoes a color change (pink
dance with internationally recognized principles on standard-
to colorless or very faint blue-green) in the presence of excess
ization established in the Decision on Principles for the
+2
ceric ion. The amount of Fe titrated in the reaction:
Development of International Standards, Guides and Recom-
12 14 13 13
Fe 1Ce →Fe 1Ce (2)
mendations issued by the World Trade Organization Technical
+6
is a direct measure of Mo concentration.
Barriers to Trade (TBT) Committee.
4. Significance and Use
2. Referenced Documents
4.1 This test method sets forth a procedure by which
2.1 ASTM Standards:
catalyst samples can be compared either on an interlaboratory
D1193 Specification for Reagent Water
or intralaboratory basis. It is anticipated that catalyst producers
and users will find this method of value.
This test method is under the jurisdiction of ASTM Committee D32 on
Catalysts and is the direct responsibility of Subcommittee D32.03 on Chemical
5. Interferences
Composition.
5.1 Elements such as As, Sb, Cr, Fe, Ti, V, U, or W can
Current edition approved June 1, 2021. Published June 2021. Originally
approved in 1980. Last previous edition approved in 2015 as D3943 – 10(2015).
interfere in this analysis. If serious interference occurs, it will
DOI: 10.1520/D3943-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3943 − 21
be necessary to isolate the molybdenum from the interfering 7.8 Mercuric Chloride (HgCl ) Solution, approximately
species prior to measurement. 2 %. Dissolve 10 g of mercuric chloride (HgCl ) in water.
Transfer to a 500 mL volumetric flask, dilute to volume, and
5.2 Organics and nitrates can interfere or react with the
mix.
zinc-amalgam if the sulfuric acid treatment is not properly
carried out as described in 9.1.
7.9 Molybdenum Standard Solution—Dissolve 1.0 g,
weighed to the nearest 0.1 mg, of sodium molybdate dihydrate
6. Apparatus
(Na MoO ·2H O) in water containing 10 mL of H SO ,
2 4 2 2 4
transfer to a 1 L volumetric flask, dilute to volume, and mix
6.1 Beakers, 250 mL.
(1 mL = 0.5948 mg MoO ).
6.2 Jones Reductor Column, 30 cm long by 2 cm in outer
4 7.10 Phosphoric Acid (H PO ), concentrated—Mix130mL
3 4
diameter, with a 100 mL reservoir. Attach a piece of vinyl
of concentrated H SO with 250 mL of water. Add the acid
2 4
tubing to the end of the delivery tube long enough to extend to
slowly with constant stirring. Add 140 mL of concentrated
the bottom of the filtering flask (see Test Method E507).
H PO and 15 mL of a saturated solution of MnSO (approxi-
3 4 4
6.3 Vacuum Filtering Flask, heavy-walled, 1000 mL.
mately 60 g/100 mL). Dilute to 1000 mL with water.
6.4 Buret, 50 mL, Class A (0.1 mL divisions).
7.11 Potassium Permanganate (KMnO ), approximately
0.1 M solution.
6.5 Stirring Motor, magnetic, and TFE-fluorocarbon-
covered stirring bars, 7.11 by 14.2 mm.
7.12 Sulfuric Acid (H SO ), concentrated, 1 + 1 and 1 + 19,
2 4
dilutions with water, corresponding to 18 and 1.8 N solutions,
7. Reagents
respectively. Cautiously add the concentrated sulfuric acid to
the water, mix well, and allow to cool.
7.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
7.13 Sulfuric Acid (H SO ), dilute, 1 + 99, warm, dilutions
2 4
all reagents shall conform to the specifications of the Commit-
with water, corresponding to 0.18 N solution. Cautiously add
tee onAnalytical Reagents of theAmerican Chemical Society,
the concentrated sulfuric acid to the water and mix well.
where such specifications are available. Other grades may be
7.14 Zinc Metal, 20 mesh, low iron content.
used provided it is first ascertained that the reagent is of
sufficiently high purity to permit its use without lessening the
8. Sampling
accuracy of the determination.
7.2 Purity of Water—Unless otherwise indicated, references 8.1 The selection of a representative analytical sample from
to water shall be understood to mean reagent water conforming the bulk material is outside the scope of the present method. It
to Specification D1193. is presumed that parties using this test method for comparison
purposes will have agreed on the selection of an analytical
7.3 Ceric Sulfate, 0.10 N standardized using sodium molyb-
sample which is appropriate to their needs.
date following the procedure given in Annex A2.
8.2 Pulverize the analytical sample to pass a 150 µm (No.
NOTE 1—Refer to Section 8 on Hazards in Practice D7442 for hazards
100) sieve. Ignite the pulverized sample for 30 min at 550 °C
associated with handling of acids.
in a muffle furnace. Allow to cool in a desiccator.
7.4 Ferric Ammonium Sulfate Solution—[FeNH (SO ) ·12
4 4 2
H O]—Dissolve 200 g of [FeNH (SO ) ·12 H O] in 1000 mL
2 4 4 2 2
9. Procedure
of water containing 20 mL of concentrated sulfuric acid. Add
9.1 Transfer a 0.75 g specim
...

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: D3943 − 10 (Reapproved 2015) D3943 − 21
Standard Test Method for
Total Molybdenum in Fresh Alumina-Base Catalysts
This standard is issued under the fixed designation D3943; 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
1.1 This test method covers the determination of molybdenum in alumina-base catalysts and has been cooperatively tested at
molybdenum concentrations from 8 to 18 weight %, expressed as MoO . Any component of the catalyst other than molybdenum
such as iron, tungsten, etc., which is capable of being oxidized by either ferric or ceric ions after being passed through a
zinc-amalgam reductor column (Jones reductor) will interfere.
1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 Many catalysts that contain molybdenum also contain other metals, nickel for example, that may be regulated by the EPA. Go
to the material safety data sheet for the catalyst material being analyzed. More information can be found at EPA.gov. Additional
information on nickel containing catalysts can be found in Test Method D4481.
1.4 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D4481 Test Method for Total Nickel in Fresh Alumina-Base Catalysts
D7442 Practice for Sample Preparation of Fluid Catalytic Cracking Catalysts and Zeolites for Elemental Analysis by Inductively
Coupled Plasma Optical Emission Spectroscopy
E173 Practice for Conducting Interlaboratory Studies of Methods for Chemical Analysis of Metals (Withdrawn 1998)
E507 Test Method for Determination of Aluminum in Iron Ores by Flame Atomic Absorption Spectrometry
3. Summary of Test Method
3.1 The catalyst is digested in hot sulfuric acid to dissolve molybdenum, destroy organic matter, and to expel nitrates if present.
This test method is under the jurisdiction of ASTM Committee D32 on Catalysts and is the direct responsibility of Subcommittee D32.03 on Chemical Composition.
Current edition approved Dec. 1, 2015June 1, 2021. Published December 2015June 2021. Originally approved in 1980. Last previous edition approved in 20102015 as
D3943D3943 – 10–10.(2015). DOI: 10.1520/D3943-10R15.10.1520/D3943-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3943 − 21
The acid solution is diluted and passed through an amalgamated zinc column (Jones reductor) into a receiving flask containing an
+6 +3
excess of ferric ammonium sulfate. The column quantitatively reduces the molybdenum (Mo to Mo ) which in turn is reoxidized
in the receiving flask according to the reaction:
13 13 16 12
Mo 13Fe →Mo 13Fe (1)
+3
3.2 The ferrous ion produced (three per Mo oxidized) is titrated with standard ceric sulfate solution in the presence of ferroin
indicator. The indicator undergoes a color change (pink to colorless or very faint blue-green) in the presence of excess ceric ion.
+2
The amount of Fe titrated in the reaction:
12 14 13 13
Fe 1Ce →Fe 1Ce (2)
+6
is a direct measure of Mo concentration.
4. Significance and Use
4.1 This test method sets forth a procedure by which catalyst samples can be compared either on an interlaboratory or
intralaboratory basis. It is anticipated that catalyst producers and users will find this method of value.
5. Interferences
5.1 Elements such as As, Sb, Cr, Fe, Ti, V, U, or W can interfere in this analysis. If serious interference occurs, it will be necessary
to isolate the molybdenum from the interfering species prior to measurement.
5.2 Organics and nitrates can interfere or react with the zinc-amalgam if the sulfuric acid treatment is not properly carried out as
described in 9.1.
6. Apparatus
6.1 Beakers, 250-mL.250 mL.
6.2 Jones Reductor Column, 30-cm30 cm long by 2 cm in outer diameter, with a 100-mL100 mL reservoir. Attach a piece of vinyl
tubing to the end of the delivery tube long enough to extend to the bottom of the filtering flask (see Test Method E507).
6.3 Vacuum Filtering Flask, heavy-walled, 1000-mL.1000 mL.
6.4 Buret, 50-mL,50 mL, Class A (0.1-mL(0.1 mL divisions).
6.5 Stirring Motor, magnetic, and TFE-fluorocarbon-covered stirring bars, 7.11 by 14.2 mm.
7. Reagents
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water conforming to
Specification D1193.
7.3 Ceric Sulfate, 0.10 N standardized using sodium molybdate following the procedure given in Annex A2.
The sole source of supply of the apparatus known to the committee at this time is Part No. 8035-J10 from Thomas Scientific, 99 High Hill Rd. at 295, Swedesboro, NJ
08085. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at
a meeting of the responsible technical committee, which you may attend.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed by
the American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
D3943 − 21
NOTE 1—Refer to Section 8 on Hazards in Practice D7442 for hazards associated with handling of acids.
7.4 Ferric Ammonium Sulfate Solution—[FeNH (SO ) ·12 H O]—Dissolve 200 g of [FeNH (SO ) ·12 H O] in 1000 mL of water
4 4 2 2 4 4 2 2
containing 20 mL of concentrated sulfuric acid. Add potassium permanganate solution dropwise until a pink color persists for 1
min.
7.5 Ferroin Indicator, 0.025 M solution of 1, 10-phenanthroline ferrous sulfate complex.
7.6 Hydrochloric Acid (HCl), concentrated.
7.7 Jones Reductor Amalgam.
7.8 Mercuric Chloride (HgCl ) Solution, approximately 2 %. Dissolve 10 g of mercuric chloride (HgCl ) in water. Transfer to a
2 2
500–mL500 mL volumetric flask, dilute to volume, and mix.
7.9 Molybdenum Standard Solution—Dissolve 1.0 g, weighed to the nearest 0.1 mg, of sodium molybdate dihydrate
(Na MoO ·2H O) in water containing 10 mL of H SO , transfer to a 1-L1 L volumetric flask, dilute to volume, and mix (1 mL
2 4 2 2 4
= 0.5948 mg MoO ).
7.10 Phosphoric Acid (H PO ), concentrated—Mix 130 mL of concentrated H SO with 250 mL of water. Add the acid slowly
3 4 2 4
with constant stirring. Add 140 mL of concentrated H PO and 15 mL of a saturated solution of MnSO
...