Absorption Kinetics of Carbon Dioxide in Amine Solvents and Their Measurement Techniques: A Review

The process of carbon dioxide (CO₂) absorption by alkanol amine solutions is currently the most favourable compared to other CO₂ capture technologies, as it is efficient, well established, and economically feasible. Nevertheless, the existing operational CO₂ absorption units are suffering from a number limitations including high energy penalty, solvent loss and degradation. Therefore, research is ongoing to find alternative amine solvents or solvent blends that can outperform the existing and common solvents in terms of absorption capacity, rate of reaction with CO₂ and cyclic energy requirements. This paper provides an overview of the kinetics parameters for CO₂ absorption into amine-based solvents and outlines the methods used in the literature for measuring the absorption capacity, rate of the reaction, rate constants and rate order, for the reaction of CO₂ with amine solvents. The paper discusses each measurement technique highlighting its strengths and limitations in terms of type and concentration of amine solvents, gas and liquid flowrates, CO₂ partial pressures, and operating temperature ranges. The outcome of this paper can assist researchers and engineers understand and effectively design the CO₂/amine absorption set-up by selecting suitable reactors for certain types of solvents and set of operating conditions.