ASTM D3766-24a

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: D3766 − 24a
Standard Terminology Relating to
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Catalysts and Catalysis
This standard is issued under the fixed designation D3766; 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.
DISCUSSION—A carrier may have or contribute to catalytic activity.
1. Scope
1.1 This terminology covers definitions of terms related to
catalyst substrate, n—less preferred alternative term for cata-
catalysts and catalysis.
lyst carrier.
NOTE 1—The Manual of Symbols and Terminology for Physicochemi-
catalyst support, n—less preferred alternative term for catalyst
cal Quantities and Units presents authoritative descriptions of many terms
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carrier.
used in the field of catalysis.
1.2 This international standard was developed in accor-
conversion, n—the amount of a feed reagent consumed rela-
dance with internationally recognized principles on standard-
tive to the total amount of the reagent fed to the reactor.
ization established in the Decision on Principles for the
Calculated as the difference between the molar flowrate of
Development of International Standards, Guides and Recom-
the reagent fed to the reactor minus the molar flowrate from
mendations issued by the World Trade Organization Technical
the reactor, divided by the molar flowrate fed to the reactor.
Barriers to Trade (TBT) Committee.
crush strength, n—in catalysis, a measure of the resistance of
2. Terminology
formed catalysts or catalyst carriers, either singly or in bulk,
2.1 Definitions: to loss of form when subjected to a compressive force.
abrasion, n—the gradual removal of material from a surface
DISCUSSION—Formed catalysts may include tablets, spheres,
extrudates, rings, pellets, etc. and should be distinguished from
due to friction typically generating fine particles. Note:
powders and granules.
abrasion and attrition are often used interchangeably.
density, packing (bulk), n—the ratio of the mass of a
activity, n—of a catalyst, the measure of the rate of a specific
collection of discrete pieces of solid material to the sum of
catalytic reaction conducted in the presence of a catalyst.
the volumes of: the solids in each piece, the voids within the
attrition, n—the wearing down of particles by grinding against
pieces, and the voids among the pieces of the particular
each other producing chips and fine particles. Note: abra-
collection.
sion and attrition are often used interchangeably.
density, particle (envelope), n—the ratio of the mass of a
calcine, v—in catalysis, to heat a material to a high temperature
particle to the sum of the volumes of: the solid in each piece
causing a physical or chemical change, for example, loss of
and the voids within each piece, that is, within close-fitting
moisture and volatile matter, or a phase change, or both.
imaginary envelopes completely surrounding each piece.
catalyst bed support, n—an essentially inert plate, grid,
density, skeletal, n—the ratio of the mass of discrete pieces of
particulate bed, or other structural component designed to
solid material to the sum of the volumes of: the solid
hold up or bear a quantity of catalyst in a catalytic reactor.
material in the pieces and closed (or blind) pores within the
catalyst carrier, n—a solid, generally porous material upon the
pieces.
surface or into the voids of which catalytic materials are
density, theoretical, n—the ratio of the mass of a collection of
placed to create the desired catalyst.
discrete pieces of solid material to the sum of the volumes of
said pieces, the solid material having an ideal regular
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This terminology is under the jurisdiction of ASTM Committee D32 on
arrangement at the atomic level.
Catalysts and is the direct responsibility of Subcommittee D32.92 on Nomenclature
and Definitions.
Current edition approved Feb. 1, 2024. Published March 2024. Originally envelope, n—of a particle in catalysis, a theoretical surface
approved in 1979. Last previous edition approved in 2024 as D3766 – 24. DOI:
that encloses the particle and that bridges openings to the
10.1520/D3766-24A.
interior of the particle.
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“The Manual of Symbols and Terminology for Physicochemical Quantities and
Units—Appendix II. Definitions, Terminology and Symbols in Colloid and Surface
fragmentation, n—the breaking of a solid catalytic material
Chemistry. Part II: Heterogeneous Catalysis,” Pure and Applied Chemistry, Vol 46,
No. 1, 73–90(1976). into two or more smaller particles.
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