High-Purity Ethylene Production from Ethane/Ethylene Mixtures at Ambient Conditions by Ethane-Selective Fluorine-Doped Activated Carbon Adsorbents

Energy-efficient separation of light alkanes from alkenes is considered as one of the most important separations of the chemical industry today due to the high energy penalty associated with the applied conventional cryogenic technologies. This study introduces fluorine-doped activated carbon adsorbents, where elemental fluorine incorporation into the carbon matrix plays a unique role in achieving high ethane selectivity. This enhanced selectivity arises from specific interactions between surface-doped fluorine atoms and ethane molecules, coupled with porosity modulation. Consequently, an equilibrium ethane/ethylene selectivity of as high as 3.9 at 298 K and 1 bar was achieved. Furthermore, polymer-grade ethylene (purity >99.99%) with a productivity of 1.6 mmol/g was obtained in a breakthrough run at ambient conditions from a binary ethane/ethylene (1/9 v/v) mixture. The ethane selectivity of the fluorine-doped carbons was further elucidated through Monte Carlo simulations and density contours of the adsorbed components. In addition to the high ethane selectivity, the adsorbents exhibited a hydrophobic surface, high stability under moisture, and excellent regenerability over multiple adsorption-desorption cycles under both equilibrium and dynamic conditions, demonstrating a sustainable performance.