A robust ethane-selective hypercrosslinked porous organic adsorbent with high ethane capacity

Abstract

While preferential adsorption of ethane (C₂H₆) over ethylene (C₂H₄) is more advantageous in industrial separation technology, most porous materials such as metal–organic frameworks, covalent–organic frameworks, and hydrogen-bonded organic frameworks provide C₂H₄-selective performance, and they suffer from poor stability and large-scale synthesis problems required for practical applications. Herein, we report the synthesis and C₂ gas separation properties of seven robust hypercrosslinked polymers (HCPs; HCP_TPB, HCP_TMPB, HCP_BCMBP, HCP_p-DCX, HCP_m-DCX, HCP_o-DCX, and HCP_CMBA) prepared from inexpensive starting monomers through the facile Friedel–Crafts reaction. Notably, HCP_TPB exhibited the highest C₂H₆ capture capacity among C₂H₆-selective metal-free adsorbents. The preferential C₂H₆ adsorption is associated with enhanced C–H⋯π interactions in the intrinsically nonpolar environments created by aromatic rings. In addition, a linear relationship between ethane uptake and surface area in porous organic frameworks was established for the first time. Breakthrough experiments demonstrated the selective separation of C₂H₆ from C₂H₆/C₂H₄ mixtures and the recyclability of HCP_TPB and HCP_TMPB. This work provides a design basis for the development of scalable, robust C₂H₆-selective adsorbents by tuning the nonpolar pore environment.