A new approach of ionic liquid containing polymer sorbents for post-combustion CO2 scrubbing

Room temperature task-specific ionic liquids (TSIL) of 1-(2-hydroxylethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Im21OH][Tf2N]) or 2-hydroxyethyl(dimethyl)-isopropylammonium bis(trifluoromethylsulfonyl)imide ([Nip,211OH][Tf2N]) with superbase, 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU), has been combined with Torlon® powders (<106 um) to simulate the potential benefits of integrating equimolar amounts of ionic liquids and superbase into hollow fibers in terms of both sorption uptake and kinetics. Approximately 44 wt% of an equimolar [Im21OH][Tf2N]-DBU in Torlon® powders achieved CO2 sorption uptake of 0.57 mmol CO2/g at a CO2 feed pressure of 0.1 atm and at 35 °C. Similar amounts of an equimolar [Nip,211OH][Tf2N]-DBU in Torlon® powders showed CO2 sorption uptake of 0.45 mmol CO2/g at the same condition. The half time (time to reach Mt/M∞ of 0.5) for Torlon®, Torlon®(62 mg)/[Im21OH][Tf2N]-DBU(48 mg) and [Im21OH][Tf2N]-DBU at low feed pressure (∼1.5 psia CO2) was approximately 4, 55, and 298 s, respectively demonstrating that imbibing an equimolar [Im21OH][Tf2N]-DBU into polymer powders substantially improved sorption kinetics compared to the neat counterpart. The sorption half time is expected to be even shorter for fibers with smaller characteristic polymer morphology domains. The current study also demonstrates a new experimental approach to characterize CO2 sorption in an equimolar mixture of ionic liquids and superbase.