CO₂ capture performance and foaming mechanism of modified amine-based absorbents: A study based on molecular dynamics

Efficient and sustainable CO₂ capture technologies are key to addressing global climate change; however, existing amine-based absorbents still have limitations in terms of reaction efficiency and energy consumption. This study investigates the modification of amine-based absorbents, including monoethanolamine (MEA), diethanolamine (DEA), and N-methyldiethanolamine (MDEA), using the surfactant Fatty Alcohol Polyoxyethylene Ether-9 (AEO-9). The CO₂ capture performance, product accumulation, and molecular interaction mechanisms were systematically examined. The results show that the inclusion of AEO-9 reduces the surface tension of the absorbent by 41.4 %–49.1 %, enhancing the foaming properties and improving CO₂ removal efficiency by 22.3 %–41.5 %. Additionally, the absorption performance of some rate-amine blends after foaming is better than pure MEA, suggesting their potential to reduce energy consumption and mitigate equipment corrosion. ¹³C NMR and FTIR characterization confirmed the formation and accumulation of reaction products. Molecular dynamics simulations further revealed that the surfactant enhances molecular cooperation by optimizing the density and dynamic characteristics of the solvation shell. Meanwhile, the modified system showed increased hydrogen bond length and bond angle, weakening network rigidity and improving intermolecular mobility. This study demonstrates the potential of foaming absorbents in CO₂ capture and introduces a novel approach to enhancing absorbent performance through interfacial regulation and microstructural optimization, providing important theoretical and practical insights for the development of efficient, low-energy carbon capture technologies.