CO₂ Capture Using PIM‑1 Hollow Fiber Sorbents with Enhanced Performance by PEI Infusion

This paper describes hollow fiber sorbents made of the parent polymer of intrinsic microporosity, PIM-1, using a spinning method designed to control the formation of dense barrier layers followed by a simple post treatment with polyethylenimine (PEI) for further improvement of CO2 uptake. The overall process involved solvent-moderated sheath-core spinning with a variation of core/bore flow rates and quench bath temperatures. Dope compositions to promote micropore interconnectivity were optimized by controlling the dope nonsolvent concentration. Under optimized conditions, undesirable skin layers were not formed, avoiding associated mass transfer resistance. The resulting PIM-1 hollow fiber sorbents achieved good CO2 uptake, with maximum equilibrium capacities of 2.8 mmol-CO2/g-fiber. CO2 sorption kinetics were dependent on PEI loading, allowing the designer to balance between capacity and uptake rate, a control feature unavailable with the pure PIM fiber sorbent