Gas Adsorption Selectivity in Topologically Disordered Metal–Organic Frameworks

Disordered metal–organic frameworks are emerging as an attractive class of functional materials, however their applications in gas storage and separation have yet to be fully explored. Here, we investigate gas adsorption in the topologically disordered Fe-BTC framework and its crystalline counterpart, MIL‑100. Despite their similar chemistry and local structure, they exhibit very different sorption behaviour towards a range of industrial gases, noble gases and hydrocarbons. Virial analysis reveals that Fe-BTC has enhanced interaction strength with guest molecules compared to MIL‑100. Most notably, we observe striking discrimination between the adsorption of C₃H₆ and C₃H₈ in Fe‑BTC, with over a twofold increase in the amount of C₃H₆ being adsorbed than C₃H₈. Thermodynamic selectivity towards a range of industrially relevant binary mixtures is probed using ideal adsorbed solution theory (IAST). Together, this suggests the disordered material may possess powerful separation capabilities that are rare even amongst crystalline frameworks.