Ethane-selective metal-organic frameworks for one-step purification of ethylene

Abstract

Ethylene/ethane separations remain among the most energy-intensive operations in the petrochemical value chain, owing to their close molecular sizes, polarizabilities, and volatilities. While cryogenic distillation is industrially entrenched, adsorption-based processes promise substantial energy savings and simpler flowsheets, particularly when impurity-targeted adsorbents are employed. This comprehensive review systematically examines recent advancements in ethane-selective MOF adsorbents that enable one-step purification of polymer-grade ethylene directly from cracked-gas mixtures. We delineate three fundamental separation mechanisms that govern selective ethane capture: (i) strategic incorporation of electronegative binding sites for enhanced C-H•••site interactions, (ii) engineering of low-polarity hydrophobic pore environments to leverage differential van der Waals interactions, and (iii) utilization of framework flexibility and gateopening phenomena that preferentially accommodate ethane molecules. The review critically evaluates representative MOF systems across key performance metrics including equilibrium uptake capacities, IAST-predicted selectivity values, and experimental breakthrough behaviors under mixed-gas conditions. By establishing clear structure-property relationships and identifying emerging design principles, this work provides valuable insights for the rational development of nextgeneration ethane-selective adsorbents with optimized separation performance.