Ethane/ethylene separation in a metal-organic framework with iron-peroxo sites

The separation of ethane from its corresponding ethylene is an important, challenging, and energy-intensive process in the chemical industry. Here we report a microporous metal-organic framework, iron(III) peroxide 2,5-dioxido-1,4-benzenedicarboxylate [Fe₂(O₂)(dobdc) (dobdc⁴⁻: 2,5-dioxido-1,4-benzenedicarboxylate)], with iron (Fe)–peroxo sites for the preferential binding of ethane over ethylene and thus highly selective separation of C₂H₆/C₂H₄. Neutron powder diffraction studies and theoretical calculations demonstrate the key role of Fe-peroxo sites for the recognition of ethane. The high performance of Fe₂(O₂)(dobdc) for the ethane/ethylene separation has been validated by gas sorption isotherms, ideal adsorbed solution theory calculations, and simulated and experimental breakthrough curves. Through a fixed-bed column packed with this porous material, polymer-grade ethylene (99.99% pure) can be straightforwardly produced from ethane/ethylene mixtures during the first adsorption cycle, demonstrating the potential of Fe₂(O₂)(dobdc) for this important industrial separation with a low energy cost under ambient conditions.