Chemisorption Contribution of Support Materials on CO2 Capture of Amine-Impregnated Adsorbents

Abstract

CO2 capture via amine-impregnated adsorbents constitutes a pivotal technological strategy for mitigating CO2 emissions. However, the reaction mechanisms between CO2 and amine-impregnated adsorbents, particularly the potential role of support materials in these processes, remains inadequately understood. This study systematically investigates the influence of support surface chemistry on the CO2 adsorption behavior of amine-impregnated adsorbents, utilizing both inorganic (SiO2, Al2O3) and organic (XAD-4, activated carbon) supports. Our findings reveal significant variations in CO2 adsorption capacity, amine utilization efficiency, desorption characteristics, and desorption energy demands across the two categories of supports. These discrepancies are attributed to fundamentally distinct chemisorption pathways: inorganic-supported adsorbents exclusively form carbamates upon reaction with CO2, while organic-supported adsorbents concurrently generate carbamates, carbamic acids, and (bi)carbonates. This distinct chemisorption mechanism associated with organic supports results in enhanced CO2 uptake, improved amine utilization efficiency, and reduced optimal adsorption temperatures and adsorption heat. Furthermore, the study conclusively establishes that the unique chemisorption behavior on organic supports is attributable to the active participation of hydroxyl groups in the CO2 adsorption process, a phenomenon absent in inorganic supports. This support-dependent chemisorption behavior enables targeted adsorbent optimization, laying the foundation for next-generation amine-impregnated adsorbent to perform efficiently under dynamic conditions.