Efficient Separation of C₂H₆/C₂H₄ and C₃H₈/C₂H₆/CH₄ Light Hydrocarbons Using Robust Porous Polymer Networks for C₂H₄...

The efficient production of ultrahigh-purity C₂H₄ and CH₄, which are vital feedstocks for industrial processes and alternative energy, is increasingly in demand but remains challenging. Cryogenic distillation has been widely utilized for this purpose; however, it imposes a substantial energy burden. Herein, we report four robust porous polymer networks (PPNs), namely, PPN-35, PPN-45, PPN-55, and PPN-65, for the purification of C₂H₄ from C₂H₆/C₂H₄ mixtures and CH₄ from C₃H₈/C₂H₆/CH₄ mixtures. PPN-35, PPN-45, PPN-55, and PPN-65 exhibit IAST selectivities of 1.67, 1.43, 1.24, and 1.34 for C₂H₆/C₂H₄; 345.33, 199.16, 135.21, and 269.93 for C₂H₆/CH₄; 20.17, 79.73, 31.77, and 15.98 for C₃H₈/C₂H₆; and 61907.55, 284358.59, 18175.83, and 19484.73 for C₃H₈/CH₄, respectively. These values demonstrate that the materials are promising candidates to replace the widely used cryogenic distillation process. To the best of our knowledge, the C₂H₆/C₂H₄ selectivity of 1.67 achieved by PPN-35 is the highest reported for any PPN, and the C₂H₆/CH₄, C₃H₈/C₂H₆, and C₃H₈/CH₄ selectivities surpassed all those of sorbents reported in the literature. Each of the four PPNs exhibits high adsorption capacities, and their practical usability was validated through breakthrough experiments, yielding >99% purity for both C₂H₄ and CH₄. This work paves the way for exploring PPNs for light hydrocarbon separation.