Improved Prediction of Reaction Kinetics for Amine Absorbent-based Carbon Capture using Reactive Site-based Transition State Conformer Search Method

There is no doubt that carbon emissions are one of the greatest challenges facing humanity today. Carbon capture, utilization, and storage is an effective way to achieve carbon neutrality. However, the commonly used commercial absorbents for post-combustion captures still have some limitations such as low chemical absorption rate constants. In this paper, a universal reaction kinetic model is developed for amine-based carbon capture based on the transition state theory, density functional theory, and hybrid solvation model. The developed reaction kinetic model is applicable to a wide range of amine-solvent solutions involving primary/secondary/tertiary amines and aqueous/nonaqueous solvents. The key contribution of this work is developing a reactive site-based transition state conformer search method, which has greatly improved the prediction accuracy of the reaction kinetic model from R2=0.819 to R2=0.943 based on a dataset of 21 various amine-solvent solutions. The results highlight the critical impacts of the transition state conformational isomers on amine-based CO2 chemical absorption rate constants.