Hydrogen-Bonded Organic Frameworks (HOFs) for C2 Gas Separation and Purification

Industrial separation of C2 gas mixtures, particularly challenging C₂H₂/CO₂, C₂H₂/C₂H₄, and C₂H₆/C₂H₄ separations, occupies a considerable portion of energy consumption in chemical production, highlighting the urgent need for low-carbon separation technologies. Adsorptive separation using functional porous materials provides a promising ambient-condition alternative to cut energy demand dramatically while maintaining high purification efficiency. Beyond the extensively studied metal-organic frameworks (MOFs), hydrogen-bonded organic frameworks (HOFs) have emerged as a rising class of crystalline porous materials for hydrocarbon separation, thanks to their tunable framework chemistry, precisely engineered pore environments, facile solution processability, and excellent regeneration capability. These unique advantages have enabled HOFs to deliver competitive performance in demanding separation scenarios ranging from selective C₂H₂ capture to C₂H₆-selective olefin purification. Herein, we present a timely and comprehensive overview of recent advances in HOF-based sorbents for C2 gas separation and purification, covering conventional binary systems (C₂H₂/CO₂, C₂H₂/C₂H₄, and C₂H₆/C₂H₄) as well as more complex multicomponent systems (three-component C₂H₂/CO₂/C₂H₄, C₂H₂/ C₂H₆/C₂H₄, and seven-component CH₄/C₂H₄/C₂H₆/C₃H₆/C₃H₈/CO₂/H₂). We further elucidate the critical structure-performance relationships governing different separation mechanisms and highlight key bottlenecks and future research directions to guide the development of HOFs for industrial gas separation.