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

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.