The determination of the pore size distribution of an activated carbon using Dubinin-Astakhov analysis of CO2 adsorption at 273 K

Activated carbons are porous carbonaceous materials that serve a broad range of practical applications including catalysis, gas purification and separation, and other vapour and liquid phase adsorption-based technologies. The pore structure, as well as the specific surface area, of these materials can vary greatly between carbons activated using different methods and under differing conditions, and it depends also on the choice of raw material. Activated carbons can contain pores in the macro- (d > 50 nm), meso- (50 nm > d > 2 nm) and microporous (d < 2 nm) regimes, according to the IUPAC classification . The pore structure of a particular carbon is crucial to its practical application and so the determination of the pore size distribution (PSD) is an important characterization measurement in the study of these materials. In addition, activated carbons are non-crystalline materials that cannot be characterized easily by X-ray powder diffraction. As a result, alternative methods for the determination of their microstructure are of significant interest. The measurement of the adsorption behaviour of different probe molecules, and the subsequent analysis of the data to obtain a PSD, is one of the alternative methods that can complement small angle scattering and other characterisation techniques. So-called ‘classical’ methods of pore size distribution determination include Dubinin-Astakhov (DA), Dubinin-Radushkevich (DR) and Horvoe-Kawazoe (HK) Analysis .