Influence of segregated adsorption on mixture diffusion in DDR zeolite

Abstract Grand Canonical Monte Carlo simulations for adsorption of CO 2 /CH 4 , CH 4 /N 2 , and CO 2 /Ar mixtures in DDR zeolite show that the window regions contain practically no CH 4 or Ar; these molecules are predominantly adsorbed within the cages. CO 2 and N 2 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 CO 2 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.

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