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.
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