Modeling of CO2 Solubility in Tertiary Amine Solvents Using pKa

Abstract

Tertiary amines are widely used to capture CO2 from the gases of high-pressure processes because these compounds have high CO2 solubilities at high pressures of 0.5–1 MPa and low CO2 absorption heats compared to primary and secondary amines. CO2 solubility model for tertiary amine solvents was developed using pKa. This study used selected aqueous solutions of tertiary alkanolamines, tertiary cyclic amines, and tertiary diamines as solvents for modeling. Chemical equilibrium constants were correlated with a linear function of pKa. The generalized parameters provide a method to predict CO2 solubility in a tertiary amine solution from the pKa of the amine.