Influence of segregated adsorption on mixture diffusion in DDR zeolite

Grand Canonical Monte Carlo simulations for adsorption of CO2/CH4, CH4/N2, and CO2/Ar mixtures in DDR zeolite show that the window regions contain practically no CH4 or Ar; these molecules are predominantly adsorbed within the cages. CO2 and N2 molecules adsorb both within the cages and at the window regions. Due to segregated adsorption, the ideal adsorbed solution theory is unable to predict the mixture loadings accurately. Molecular dynamics simulations show that CO2 molecules that are strongly adsorbed at the windows hinder the inter-cage diffusion of partner molecules in mixtures; this effect is not described by the Maxwell–Stefan theory.