(47e) Investigating the Competitive Sorption and Plasticization Effects of Hyperaged 3D Canal Ladder Polymers in Complex CO2 Gas Mixtures for Carbon Capture Applications

Carbon dioxide (CO₂) separation from natural gas, biogas, and flue gas stands as a critical industrial process. Membrane technology has emerged as an energy-efficient and environmentally benign alternative to traditional amine absorption methods for CO₂ separations. Efforts to improve CO₂ separation have primarily focused on enhancing the affinity of membrane materials for CO₂, often through the incorporation of CO2-affinity functional groups. Herein, we focused on enhancing the CO₂/CH₄ size-sieving effects of microporous hydrocarbon polymers synthesized via catalytic arene-norbornene annulation (CANAL) polymerization, by leveraging on the physical aging process. While typically viewed as an undesired phenomenon in glassy polymers, physical aging here led to a remarkable 3300% boost in CO₂/CH₄ selectivity, with permeability still surpassing that of most commercial membranes even after aging for 180 days. Furthermore, we elucidate substantial enhancements of up to 41% in CO₂/CH₄ selectivity and 50% in combined-acid gas (CAG) selectivity (CO₂ + H₂S/CH₄) due to competitive sorption effects observed in mixed-gas tests for a hyperaged 3D CANAL polymer, allowing the materials to surpass the 2018 CO₂/CH₄ mixed-gas and CAG upper bound. Comprehensive evaluations of the stability of the polymeric membrane in the presence of high concentrations of strongly plasticizing CO₂ and H₂S are also conducted in this study. Concentration-dependent CO₂ plasticization reduces CO₂/CH₄ mixed-gas selectivity without affecting CO₂ permeability. Conversely, time-dependent plasticization has minimal impact on CO₂/CH₄ mixed-gas selectivity but increases CO₂ permeability over time. This thorough characterization of these hyperaged CANAL polymers in complex CO₂ mixtures provides invaluable insights into their performance in practical industrial processes, which would otherwise not be captured through typical pure-gas measurements.