Kinetics and mechanism of low‐concentration CO₂ adsorption on solid amine in a humid confined space

Abstract

The kinetics and mechanism of low-concentration CO 2 adsorption on a solid-supported polyethylenimine (PEI) adsorbent in a humid confined space were investigated, where the content of CO 2 was about 0.4 % (v). A flow system, equipped with a dew point meter and IR gas analyzer connected in series for online measurement, was developed and the co-adsorption performance of CO 2 and H 2 O was analyzed. It was found that the H 2 O adsorption capacity and activation energy were not significantly changed when 0.4 % (v) CO 2 was applied in the co-adsorption process, indicating that the effect of dilute CO 2 could be neglected. However, the CO 2 adsorption capacity increased with the assistance of H 2 O, and then it decreased slightly when the H 2 O content in air flow was above 1.56 % (v). This implied that the adsorption activation energy of CO 2 could be significantly reduced due to the existence of H 2 O in air flow. The direct formation of bicarbonate on the supported PEI adsorbent was favoured for the co-adsorption process of CO 2 and H 2 O.

Recent advances in direct air capture by adsorption

“…The resin also showed a faster adsorption rate and mild regeneration at approximately 70 1C. Si et al 316 fabricated a PEI-impregnated porous polymer resin and found increased CO 2 adsorption capacity with the assistance of H 2 O in a humid 4000 ppm CO 2 gas stream. Owing to their particularly high mesopore volume, amine-loaded resins typically exhibit a higher capacity.…”

Quantification of temperature-dependent CO2 adsorption kinetics in Lewatit VP OC 1065, Purolite A110, and TIFSIX-3-Ni for direct air capture

“…Other models used to describe the kinetics of DAC adsorbents include various rate order models (e.g. pseudo-first order (PFO), pseudo-second order (PSO), fractional order) [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], the Avrami model [27,28,30,31,33,34,[36][37][38][39], combined PFO and Avrami [40], and reaction-mechanism based models [41,42]. Modified forms of the shrinking core model have also been investigated, where the adsorbed phase is modelled as a product layer forming around a core of unreacted sorption sites, which shrinks as the reaction proceeds [43][44][45].…”

CO2 Adsorption Capacity of Organic Alkali Sorbent CPEI from Polyethyleneimine

“…Among various amine-based solid sorbents, polyethyleneimine-(PEI-) impregnated supports like mesoporous silicas and mesoporous molecular sieve and resin have attracted extensive attention because of their high CO 2 adsorption capacity, easy availability, and stability [23][24][25][26]. The loading of amines onto the outer and interior surfaces of the supports by impregnation is simple and has been extensively studied [27,28].…”