Amine-functionalized high-surface-area Al2O3 adsorbent for CO2 capture: Effect of the support calcination conditions

Abstract

Porous alumina has garnered interest as a substrate in the development of solid amine adsorbents for CO2 capture. However, the calcination conditions of alumina can significantly alter its properties, which in turn affects the adsorption performance of the resulting adsorbents. In this study, high-surface-area alumina was synthesized using a reverse microemulsion method. The impact of the calcination conditions on the pore structure and surface properties of the alumina precursor was examined. Additionally, the porous alumina produced under various calcination conditions served as the support for tetraethylenepentamine (TEPA) loading, and the CO2 capture performance of the resultant adsorbents was assessed. The adsorption kinetics and activation energy were analyzed, emphasizing the cyclic stability when regenerated in a realistic CO2 atmosphere. Our findings indicate that alumina calcined under an air atmosphere with a lid exhibited the highest capture capacity (reaching 89.97 mg/g after a 40 wt% TEPA loading), compared to other alumina samples. The adsorption kinetics corresponded closely with the Avrami model, yielding an activation energy (Ea) of 4.75 kJ/mol. Both alumina samples calcined in air, with and without a lid, demonstrated robust cycling stability and resistance to urea formation. The underlying anti-urea mechanisms were also elucidated in the study.