Pore size distribution and porosity of solid materials by mercury porosimetry and gas adsorption. Analysis of nanopores by gas adsorption

What is ISO 15901‑2 - Analysis of nanopores by gas adsorption about?
ISO 15901‑2 is an International Standard that discusses pore size distribution and porosity of solid materials by mercury porosimetry and gas adsorption.

ISO 15901‑2 is the second part of the ISO 15901 multi-series, and describes a method for the evaluation of porosity and pore size distribution by physical adsorption (or physisorption).

The method is limited to the determination of the quantity of a gas adsorbed per unit mass of a sample as a function of pressure at a controlled, constant temperature. Commonly used adsorptive gases for physical adsorption characterization include nitrogen, argon, and krypton at the temperatures of liquid nitrogen and argon (77 K and 87 K respectively) as well as CO2 (at 273 K).

ISO 15901‑2 focuses only on the application of the manometric method.

The method described is suitable for a wide range of porous materials. ISO 15901‑2 focuses on the determination of pore size distribution from as low as 0,4 nm up to approximately 100 nm. The determination of surface area is described in ISO 9277. The procedures which have been devised for the determination of the amount of gas adsorbed may be divided into two groups:

Those which depend on the measurement of the amount of gas removed from the gas phase, i.e., manometric (volumetric) methods
Those which involve the measurement of the uptake of the gas by the adsorbent (i.e., direct determination of the increase in mass by gravimetric methods)
Who is ISO 15901‑2 - Analysis of nanopores by gas adsorption for?
ISO 15901‑2 on analysis of nanopores by gas adsorption is useful for:

The chemical / catalyst industry
The petrochemical industry
Testing authorities for porosimetry testing
Particle technology laboratories
Polymer and ceramic industries
Manufacturers of mercury porosimeters
Why should you use ISO 15901‑2 - Analysis of nanopores by gas adsorption?
Porous materials may 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.

It is well established that the performance of a porous solid is dependent on its pore structure. Many different methods have been developed for the characterization of 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 measuring techniques of the method described in ISO 15901‑2 are similar to those described in ISO 9277 for the measurement of gas adsorption at low temperatures. However, in order to assess the full range of pore sizes including microporosity, adsorption experiments have to be performed over a wide range of pressures from the ultralow pressure range (e.g. turbomolecular pump vacuum) up to atmospheric pressure (0,1 MPa).

ISO 15901-2 helps with the methods for the estimation of pore volume, pore size distribution, and porosity.

What’s changed since the last update?
BS ISO 15901‑2:2022 supersedes BS ISO 15901‑3:2007 and BS ISO 15901‑2:2006, which are withdrawn. BS ISO 15901‑2:2022 includes some technical changes with respect to BS ISO 15901‑3:2007 and BS ISO 15901‑2:2006. These include:

The analysis of nanopores by gas adsorption which combines the characterization of both micro and mesopores is now addressed
The classification of adsorption isotherms and hysteresis loops has been updated