Reversed ethane/ethylene adsorption in a metal-organic framework via introduction of oxygen

Separation of ethane from ethylene is a very important but challenging process in the petrochemical industry. Finding an alternative method would reduce the energy needed to make 170 million tons of ethylene manufactured worldwide each year. Adsorptive separation using C₂H₆-selective porous materials to directly produce high-purity C₂H₄ is more energy-efficient. We herein report the "reversed C₂H₆/C₂H₄ adsorption" in a metal-organic framework Cr-BTC via the introduction of oxygen on its open metal sites. The oxidized Cr-BTC(O₂) can bind C₂H₆ over C₂H₄ through the active Cr-superoxo sites, which was elucidated by the gas sorption isotherms and density functional theory calculations. This material thus exhibits a good performance for the separation of 50/50 C₂H₆/C₂H₄ mixtures to produce 99.99% pure C₂H₄ in a single separation operation.