Tetraethylenepentamine (TEPA), consisting mainly of primary and secondary amines, exhibits a high CO 2 sorption capacity; however, its poor thermal stability hampers practical utilization in the temperature swing adsorption process for CO 2 capture. Here, a facile functionalization of TEPA with 1,2-epoxybutane (EB) substantially enhanced its thermal stability as well as the CO 2 adsorption kinetics. Our careful analysis on the liquid-state 13 C NMR disclosed the amine state distribution of EB-functionalized TEPA (EB-TEPA). Although the increase in tertiary amine portion induced by EB-functionalization reduced CO 2 sorption capacity, the 0.64EB-TEPA (i.e., TEPA functionalized with EB with a TEPA/EB molar ratio of 1:3)/SiO 2 showed an excellent long-term stability over the 10 consecutive cycles of adsorption/desorption processes with a CO 2 swing capacity of 2.0 mmol CO 2 g −1 under dry CO 2 /N 2 (15/85 mol/mol) feed conditions. Also, the first-principles calculation identified the configuration of modified TEPA molecules with XRD measurements, supporting an easy access of CO 2 into amine moieties of our modified TEPA molecules.

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Creating a module that achieves sustainable CO2 capture while being compatible with the existing industry is paramount in overcoming the current CO2-driven environmental issues. This paper presents the fabrication of hollow fiber sorbents (HFSs) and their respective modules to capture CO2 by the rapid thermal swing adsorption process (RTSA). Poly­(amide-imide) (PAI)/microspheric SiO2 composites were fabricated with a so-called “sieve-in-a-cage” microarchitecture which promotes CO2 diffusion. More importantly, a selected amount of 1,2-epoxybutane (EB)-functionalized poly­(ethylenimine) (PEI), denoted as 0.37EB-PEI, was incorporated into our PAI/SiO2 composites forming PAI/SiO2/0.37EB-PEI HFSs which enhanced the thermal stability with a moderate CO2 sorption uptake of 0.88 mmol CO2 g–1. The resulting HFSs were assembled into a module using either stainless steel (SS) or poly­(tetrafluoroethylene) (PTFE), and their respective CO2-capturing performances in the RTSA process were compared. The two modules had a comparable breakthrough CO2 capacity of 0.42 mmol CO2 g–1 for a wet feed mixture of CO2/He/N2 (14 mol/14 mol/72 mol) (RH 100%) and a comparable CO2 desorption efficiency (i.e., 95% desorption within 2 min) under 100% CO2 at 120 °C due to the presence of the 0.37EB-PEI; however, different thermal properties inherent to the modular materials caused the PTFE-based module to outperform the SS-based counterpart in terms of cooling, enabling the execution of an entire RTSA cycle within 8 min. Additionally, the PAI/SiO2/0.37EB-PEI/PTFE module maintained its breakthrough capacity of 0.42 mmol CO2 g–1 over five consecutive RTSA cycles, confirming its good long-term stability as well.