Reaction kinetic modeling of carbon dioxide desorption in aqueous amine solutions

Abstract

CO₂ desorption is a critical process for chemical absorption carbon capture approach, and the reaction kinetics is an important basis for the design and scale-up of desorption process. Here, kinetic modeling of CO₂ desorption in primary/secondary and tertiary amines was developed for N-(2-aminoethyl) ethanolamine (AEEA) and N,N-diethylethanolamine (DEEA), which are typical primary/secondary and tertiary amines, respectively. With the assumption that the protonated amine and carbamate or bicarbonate have the same concentration at the same moment, the desorption kinetic modeling of the two types of amines can be expressed by a pseudo-second-order equation. Quantitative speciation of the components in the absorbent was performed by ¹H and ¹³C NMR spectra, which supported the model assumptions. Furthermore, quantum chemical calculation was conducted to reveal the reaction mechanism during CO₂ desorption. Model reliability was verified by N-methyl diethanolamine (MDEA) desorption data. The Arrhenius kinetic equations for the desorption of AEEA and DEEA were determined, and the activation energies were 43.08 and 49.21 kJ/mol, respectively. The validated kinetic model of CO₂ desorption is promising to provide fundamental parameters for the design and optimization of regeneration units for CO₂ capture.