Evaluation of CO2 adsorption dynamics of polymer/silica supported poly(ethylenimine) hollow fiber sorbents in rapid temperature swing adsorption

Rapid temperature swing adsorption (RTSA) using polymer/silica supported amine hollow fiber sorbents is a new post combustion CO2 capture methodology that facilitates CO2 adsorption under nearly isothermal conditions with improved energy efficiency via heat integration. In this work, the dynamic CO2 adsorption characteristics of polymer/silica supported poly(ethylenimine) hollow fiber sorbents (CA-S-PEI-PI) are evaluated in a bench scale RTSA system. Non-isothermal fibers have breakthrough and pseudo-equilibrium CO2 capacities of 0.67 mmol/g and 1.03 mmol/g at 35 degrees C, respectively, under humid simulated flue gas conditions (100% R.H.). Prolonged exposure of the fiber sorbents to water vapor enabled the breakthrough and pseudo-equilibrium CO2 capacities to increase by 60% and 43%, respectively. Upon the removal of the heat of adsorption by flowing cooling water in the bores of the fiber sorbents, there is a substantial increase in the CO2 breakthrough capacity, reaching 1.16 mmol/g using simulated humid flue gases. The breakthrough capacity is found to increase 5% upon increasing the adsorption temperature from 35 degrees C to at 45 degrees C, suggesting improved mass transfer in the fiber sorbent at the higher temperature. The CO2 adsorption and desorption rates are shown to be very rapid, with CO2 breakthrough occurring in less than 72 s and the majority of the adsorbed CO2 desorbing in 5 min. Extensive cycling studies demonstrate that the CA-S-PEI-PI sorbents have good dynamic swing capacities, stabilizing over 60 cycles. A newly developed rechargeable post-spinning amine infusion technique provides the feasibility of recovering the CO2 adsorption performance of deactivated CA-S-PEI-PI fiber modules, by allowing for straightforward re-infusion of PEI into the deactivated sorbents. Amine-incorporated hollow fiber sorbents have good potential for practical use as scalable, adsorbing heat-exchangers. (C) 2013 Elsevier Ltd. All rights reserved.