A new approach to describe high-pressure adsorption isotherms in subcritical and supercritical conditions

International audienceIn this article, we present a new approach to describe adsorption equilibrium ofpure gases in a wide range of pressure. This approach is based on a simple statisticalmechanics treatment combining the potential theory and lattice fluid models. Theobtained equation for the calculation of the excess adsorption can predict the curveprogression of isotherms defined by the IUPAC I classification, and for those at super-critical conditions. Notwithstanding that the basic idea of the developed equation is toadapt to the adsorption equilibrium in supercritical conditions at high pressure, themodel correlates very well experimental data at low pressure in subcritical conditions.It is applicable to a wide range of pressures and fits satisfactorily the experimentaldata in a broad range of pressures and temperatures. In particular, the model predictsthe maximum of excess adsorption and its minimum. A comparison between thisapproach and two others is given