Dynamic CO₂ adsorption performance of internally cooled silica‐supported poly(ethylenimine) hollow fiber sorbents

Abstract

The dynamic adsorption behavior of CO2 under both nonisothermal and nearly isothermal conditions in silica supported poly(ethylenimine) (PEI) hollow fiber sorbents (Torlon®‐S‐PEI) is investigated in a rapid temperature swing adsorption (RTSA) process. A maximum CO2 breakthrough capacity of 1.33 mmol/g‐fiber (2.66 mmol/g‐silica) is observed when the fibers are actively cooled by flowing cooling water in the fiber bores. Under dry CO2 adsorption conditions, heat released from the CO2‐amine interaction increases the CO2 breakthrough capacity by reducing the severity of the diffusion resistance in the supported PEI. This internal resistance can also be alleviated by prehydrating the fiber sorbent with a humid N2 feed. The CO2 breakthrough capacity of prehydrated fibers is adversely affected by the release of the adsorption enthalpy (unlike the dry fibers); however, active cooling of the fiber results in a constant CO2 breakthrough capacity even at high CO2 delivery rates (i.e., high adsorption enthalpy delivery rates). In full RTSA cycles, a purity of 50% CO2 is achieved and the adsorption enthalpy recovery rate can reach ∼72%. Studies on the cyclic stability of uncooled fiber sorbents in the presence of SO2 and NO contaminants indicate that exposure to NO at 200 ppm over 120 cycles does not lead to a significant degradation of the sorbents, but SO2 exposure at a similar high concentration of 200 ppm causes 60% loss in CO2 breakthrough capacity after 120 cycles. A simple amine reinfusion technique is successfully demonstrated to recover the adsorption capacity in poisoned fiber sorbents after deactivation by exposure to impurities such SO2. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3878–3887, 2014

Stability of amine-based hollow fiber CO2 adsorbents in the presence of NO and SO2

“…The results demonstrate that fiber adsorbents exhibited excellent stability in the presence of NO. This result is consistent with previously reported results for amine-based adsorbents [11,13,14,32]. Also, the CO 2 capacity remained nearly constant over 120 cycles, revealing that detectable amine leaching did not occur in these adsorbents, as the amine groups are covalently bonded to the silica surface.…”

“…The composite polymer/silica/amine fiber adsorbents studied in this work are a new type of CO 2 capture platform [28,29] and hold promise for use as practical structured adsorbers [30]. High adsorption capacity [28], fast adsorption kinetics [31,32], and low power plant parasitic loads [33] have been associated with this type of structured adsorbent in the past. In our recent study [32], we demonstrated that 40% of the adsorption capacity in PEI impregnated silica fiber adsorbents (Torlon-S-PEI) was retained after 120 cycles upon exposure to 200 ppm SO 2 .…”

“…High adsorption capacity [28], fast adsorption kinetics [31,32], and low power plant parasitic loads [33] have been associated with this type of structured adsorbent in the past. In our recent study [32], we demonstrated that 40% of the adsorption capacity in PEI impregnated silica fiber adsorbents (Torlon-S-PEI) was retained after 120 cycles upon exposure to 200 ppm SO 2 . Consistent with other reports [13,14], exposure to NO at 200 ppm over 120 cycles did not lead to a significant degradation of the adsorbents.…”

Sponges with covalently tethered amines for high-efficiency carbon capture

“…The high amine efficiency observed here could be partially attributed to the optimized hierarchical structure of the sorbent as well as the reaction mechanism of amine and CO 2 , where the formation of bicarbonates in the presence of moisture rather than carbamates in dry CO 2 theoretically enhances the efficiency of the primary and secondary amines from 0.5 to 1. In addition, the adsorbed water may serve as a plasticizer lowering the CO 2 diffusion resistance and further improving the amine efficiency 31 .…”

Adsorptive removal of carbon dioxide using polyethyleneimine loaded glass fiber in a fixed bed

“…Polymeric-amine coatings have been widely studied due to their high selectivity towards CO 2 and high thermal stability [32,33]. Among all of the amines, polyethyleneimine (PEI) is a widely available and economical amine molecule [34][35][36]. To develop an economical and viable CO 2 adsorption system, a glass fiber that was 7 m in diameter was introduced as a supporting substrate for polyethyleneimine.…”