Adsorption equilibria of single gas and gas mixture on homogeneous surfaces: a unified approach based on statistical thermodynamics developments. Part II: extension to gas mixture adsorption

Theoretical description of single gas and gas mixture adsorption equilibria can be achieved in many different ways depending on the kind of approach (microscopic or macroscopic). In this paper, we present a statistical thermodynamics approach for the calculation of mixed gas adsorption equilibrium data on uniform surfaces. The non-ideality of both the mixed gas phase and the adsorbed phase is considered by using the Redlich-Kwong EOS associated to the classic Lorentz-Berthelot mixing rules. This is an interesting way to extend the model presented in Part I and to predict multicomponent gas adsorption equilibria for highly non-ideal systems from parameters deduced from pure gas data. We present mixture adsorption isotherms and selectivity curves calculated using our model.