Understanding ethane/ethylene adsorption selectivity in ethane-selective microporous materials

•C2H6/C2H4 adsorption selectivity cannot be higher than 2.8 based only on van der Waals interactions.•Selectivity above 3.5 can be explained by electrostatic repulsion under high confinement.•The model presented predicts the selectivity of most C2H6-selective adsorbents in the literature.