Graphene-inspired porous polymer network for ethane/ethylene separation and methane purification

C₂H₄ and CH₄ are essential for industrial applications. However, contamination with other natural gases is a challenge to their utilization. Although several sorbents have been investigated, their performance remains limited. This study introduces graphene-inspired, PPN-20, a porous polymer network (PPN) capable of separating C₂H₆/C₂H₄ and purifying CH₄ from a C₃H₈/C₂H₆/CH₄ mixture in a single step. The ultra-microporosity of PPN-20 enables preferential C-H···π interactions with C₂H₆ and C₃H₈. As a result, PPN-20 exhibits a C₂H₆ and C₃H₈ uptake of 3.93 mmol/g and 5.98 mmol/g, respectively, at 298 K and 1 bar, representing the highest reported for any PPN. It achieves ideal adsorbed solution theory (IAST) selectivities of 2.2 for C₂H₆/C₂H₄, 368.2 for C₂H₆/CH₄, 40.14 for C₃H₈/C₂H₆, and 294,336 for C₃H₈/CH₄. This selectivity, to the best of our knowledge, is the highest reported for any PPN in the case of C₂H₆/C₂H₄ separation and for any sorbent in the cases of C₂H₆/CH₄, C₃H₈/C₂H₆, and C₃H₈/CH₄ separation. Robustness tests, including breakthrough experiments, IAST calculations, etc., demonstrate the reliability of PPN-20. Its exceptional performance is attributed to precisely engineered pore sizes that enhance the trapping of guest molecules. These results will pave the way for the design of PPNs for short-chain hydrocarbon purification.