A Novel Hydrogen-Bonded Organic Framework with Highly Permanent Porosity for Boosting Ethane/Ethylene Separation

The establishment of highly permanent porosity in hydrogen-bonded organic frameworks (HOFs) is a long-standing challenge due to the fragile nature of hydrogen bonds, which delimits their broad applications in gas separation. Herein, we report a novel diamondoid HOF (termed as ZJU-HOF-10) and utilize the supercritical carbon dioxide (sc-CO2) drying method to significantly improve its permanent porosity for highly boosting ethane/ethylene (C2H6/C2H4) separation. Compared with the commonly used heat/vacuum activation, the sc-CO2 activated ZJU-HOF-10(sc) exhibits a significantly improved BET surface area of 1169 m2 g–1 over 295 m2 g–1. Such enhanced porosity in ZJU-HOF-10(sc) thus leads to a notably increased C2H6 uptake capacity (1.65 mmol g–1 at 296 K and 0.5 bar) and C2H6/C2H4 selectivity (1.9), both of which are comparable to those of the benchmark HOF-76a reported (1.69 mmol g–1 and 2.0). Theoretical calculations reveal that the inherent feature of nonpolar pore surfaces in ZJU-HOF-10(sc) plays the key role to result in stronger multipoint interactions with C2H6 over C2H4. Actual breakthrough experiments affirm that ZJU-HOF-10(sc) is capable of efficiently separating ethane from 50/50 (v/v) or 10/90 C2H6/C2H4 mixtures at ambient conditions, affording a high polymer-grade C2H4 productivity of 6.9 or 13.1 L kg–1, respectively.