Dynamic capture of low-concentration CO₂ on amine hybrid silsesquioxane aerogel

Amine hybrid silsesquioxane aerogel (AHSA) was synthesized through a single-step sol-gel process followed by supercritical drying. CO₂ adsorption performances of highly porous AHSA in 1% CO₂ were investigated. 50°C is preferred to perform the CO₂ capture of AHSA to achieve a CO₂ adsorption capacity of 3.04mmol/g (dry) or 3.84mmol/g (humid) under given conditions. A rise in adsorption gas flow rate from 300 to 700ml/min results in the decrease of CO₂ adsorption capacity from 3.04 to 2.42mmol/g. The CO₂ adsorption rate is mainly affected by the gas flow rate, while the effect of temperature can be ignored. Different with the adsorption performance, the CO₂ desorption kinetics of AHSA is mainly affected by the temperature, the effect of gas flow rate is indifferent. Water favors the CO₂ capture capability of AHSA, however, it is bad for the CO₂ adsorption and desorption kinetics. The CO₂ adsorption capacities of AHSA in 1% CO₂ are much higher than those of other amine based porous adsorbents obtained with a 1% or even higher CO₂ gas mixture. Also, AHSA has very short adsorption half time (22-55s) and low desorption temperature of 80°C, much lower than those of other amine-based adsorbents. The resulting adsorbent is dynamic and possesses excellent regenerability for low-concentration CO₂ capture.