SIST ISO 15901-1:2006

INTERNATIONAL ISO
STANDARD 15901-1
First edition
2005-12-15
Evaluation of pore size distribution and
porosimetry of solid materials by
mercury porosimetry and gas
adsorption —
Part 1:
Mercury porosimetry
Distribution des dimensions des pores et porosimétrie des matériaux
solides par porosimétrie au mercure et par adsorption de gaz —
Partie 1: Porosimétrie au mercure

Reference number
©
ISO 2005
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ii © ISO 2005 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Symbols . 4
5 Principles. 4
6 Apparatus and material. 5
7 Procedures for calibration and performance. 5
8 Procedures . 6
9 Evaluation. 9
10 Reporting . 10
Annex A (informative) Mercury porosimetry analysis results for alumina reference sample. 12
Bibliography . 18

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15901-1 was prepared by Technical Committee ISO/TC 24, Sieves, sieving and other sizing methods,
Subcommittee SC 4, Sizing by methods other than sieving.
ISO 15901 consists of the following parts, under the general title Evaluation of pore size distribution and
porosimetry of solid materials by mercury porosimetry and gas adsorption:
⎯ Part 1: Mercury porosimetry
⎯ Part 2: Analysis of mesopores and macropores by gas adsorption
⎯ Part 3: Analysis of micropores by gas adsorption
iv © ISO 2005 – All rights reserved

Introduction
In general, different pores (micro-, meso-, and macropores) can be pictured as either apertures, channels or
cavities within a solid body or as space (i.e. interstices or voids) between solid particles in a bed, compact or
aggregate. Porosity is a term which is often used to indicate the porous nature of solid material and is more
precisely defined as the ratio of the volume of the accessible pores and voids to the total volume occupied by
a given amount of the solid. In addition to the accessible pores, a solid can contain closed pores which are
isolated from the external surface and into which fluids are not able to penetrate. The characterization of
closed pores is not covered in this International Standard.
Porous materials can take the form of fine or coarse powders, compacts, extrudates, sheets or monoliths.
Their characterization usually involves the determination of the pore size distribution as well as the total pore
volume or porosity. For some purposes, it is also necessary to study the pore shape and interconnectivity and
to determine the internal and external specific surface area.
Porous materials have great technological importance, for example in the context of the following:
⎯ controlled drug release;
⎯ catalysis;
⎯ gas separation;
⎯ filtration including sterilization;
⎯ materials technology;
⎯ environmental protection and pollution control;
⎯ natural reservoir rocks;
⎯ building materials properties;
⎯ polymers and ceramic.
It is well established that the performance of a porous solid (e.g. its strength, reactivity, permeability of
adsorbent power) is dependent on its pore structure. Many different methods have been developed for the
characterization of pore structure. In view of the complexity of most porous solids, it is not surprising that the
results obtained are not always in agreement and that no single technique can be relied upon to provide a
complete picture of the pore structure. The choice of the most appropriate method depends on the application
of the porous solid, its chemical and physical nature and the range of pore size.
The most commonly used methods are as follows:
a) mercury porosimetry, where the pores are filled with mercury under pressure; this method is suitable for
many materials with pores in the appropriate diameter of 0,003 µm to 400 µm;
b) meso- and macropore analysis by gas adsorption, where the pores are characterized by adsorbing a gas,
such as nitrogen, at liquid nitrogen temperature; the method is used for pores in the approximate
diameter range of 0,002 µm to 0,1 µm (2,0 nm to 100 nm), and is an extension of the surface area
estimation technique;
c) micropore analysis by gas adsorption, where the pores are characterized by adsorbing a gas, such as
nitrogen, at liquid nitrogen temperature; the method is used for pores in the approximate diameter range
of 0,4 nm to 2,0 nm, and is an extension of the surface area estimation technique.

INTERNATIONAL STANDARD ISO 15901-1:2005(E)

Evaluation of pore size distribution and porosimetry of solid
materials by mercury porosimetry and gas adsorption —
Part 1:
Mercury porosimetry
WARNING — The use of this International Standard may involve hazardous materials, operations and
equipment. This International Standard does not purport to address all of the safety problems
associated with its use. It is the responsibility of the user of this International Standard to establish
appropriate safety and health practices and determine the applicability of regulatory limitations prior
to use.
1 Scope
This International Standard describes a method for the evaluation of the pore size distribution and the specific
[1], [2]
surface in pores of solids by mercury porosimetry according to the method of Ritter and Drake . It is a
comparative test, usually destructive due to mercury contamination, in which the volume of mercury
penetrating a pore or void is determined as a function of an applied hydrostatic pressure, which can be related
to a pore diameter.
Practical considerations presently limit the maximum applied absolute pressure to about 400 MPa
(60 000 psia) corresponding to a minimum equivalent pore diameter of approximately 0,003 µm.
The maximum diameter will be limited for samples having a significant depth due to the difference in
hydrostatic head of mercury from the top to the bottom of the sample. For the most purposes, this limit can be
regarded as 400 µm. The measurements cover interparticle and intraparticle porosity. In general, it cannot
distinguish between these porosities where they co-exist.
The method is suitable for the study of most non-wettable, by mercury, porous materials. Samples that
amalgamate with mercury, such as certain metals, e.g. gold, aluminium, reduced copper, reduced nickel and
silver, can be unsuitable for this technique or can require a preliminary passivation. Under the applied
pressure, some materials are deformed, compacted or destroyed, whereby open pores can be collapsed and
closed pores opened. In some cases, it is possible to apply sample compressibility corrections and useful
comparative data can still be obtained. For these reasons, the mercury porosimetry technique is considered to
be comparative.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3165, Sampling of chemical products for industrial use — Safety in sampling
ISO 8213, Chemical products for industrial use — Sampling techniques — Solid chemical products in the form
of particles varying from powders to coarse lumps
M 024 4/85, Quecksilber und seine Verbindungen. Merkblatt der Berufsgenossenschaft der chemischen
Industrie, Postfach 101480, D-69004 Heidelberg, Germany
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
bulk density
powder density under defined conditions
3.2
blind pore
dead-end-pore
open pore having a single connection with an external surface
3.3
closed pore
cavity not connected to the external surface
NOTE Closed pores are not covered in this International standard.
3.4
contact angle
angle that a non-wetting liquid makes with a solid material
3.5
external surface area
area of external surface including roughness but outside pores
3.6
ink bottle pore
narrow necked open pore
3.7
interconnected pore
pore which communicates with one or more other pores
3.8
internal surface area
area of internal pore walls
3.9
intraparticle porosity
ratio of the volume of open pores internal to the particle to the total volume occupied by the solid
3.10
interparticle porosity
ratio of the volume of space between particles in a powder to the apparent volume of the particles or powder
3.11
macropore
pore of internal width greater than 50 nm
3.12
mesopore
pore of internal width between 2 nm and 50 nm
3.13
micropore
pore of internal width less than 2 nm which is accessible for a molecule to be adsorbed
2 © ISO 2005 – All rights reserved

3.14
open pore
cavity or channel with access to an external surface
3.15
open porosity
ratio of the volume of open pores and voids to the total volume occupied by the solid
3.16
pore size
pore width (for example, the diameter of a cylindrical pore or the distance between the opposite walls of a slit)
that is a representative value of various sizes of the vacant space inside a porous material
NOTE One of the methods to determine pore sizes is by mercury porosimetry.
3.17
pore volume
volume of pores determined by stated method
3.18
porosimeter
instrument for measuring porosity and pore size distribution
3.19
porosimetry
methods for the estimation of porosity and pore size distribution
3.20
porosity
ratio of total pore volume to apparent volume of particle or powder
3.21
porous solid
solid with cavities or channels which are deeper than they are wide
3.22
skeletal density
mass of a powder divided by the total volume of the sample, including closed pores but excluding open pores
3.23
apparent density
mass of a powder divided by the total volume of the sample, including closed and inaccessible pores, as
determined by the stated method
3.24
powder density
mass of a powder divided by its apparent volume,
...