Study on dual-path inhibition mechanisms and multiscale structure-activity relationships in CO2 absorption kinetics of 3AP-based water-lean alcohol solutions

Water-lean absorbents have garnered significant attention for CO 2 capture due to their advantages of low corrosivity and reduced regeneration energy consumption. However, current research indicates that alcohol-based solvents generally exhibit inhibiting effects on CO 2 absorption kinetics, and the underlying suppression mechanisms remain unclear. This study employs molecular dynamics simulations to confirm that the kinetic inhibition mechanism induced by alcohols stems from dual regulatory effects where alcohol molecules form a tighter solvation shell around amines to impede zwitterion formation, while their hydrophobic alkyl groups disrupt hydrogen-bond networks to hinder zwitterion deprotonation. Further research reveals a significant structure-kinetic relationship in 3AP-alcohol solutions, where increased chain length and branching degree of alcohols correlate with slower reaction kinetics. Through integrated analysis of electrostatic potential, non-covalent interactions (NCI), and charge density, we elucidate how solvent effects inhibit the 3AP-CO 2 reaction by three mechanisms: reducing the negative electrostatic potential contribution at the amino nitrogen site, increasing transition-state bonding resistance, and decreasing charge transfer efficiency. The validity of this structure-kinetic mechanism was confirmed by our established kinetic model (AARD <4 %). This study provides a theoretical basis for the solvent screening of CO 2 poor water absorbents, which is helpful for the development process of absorbents.