Kinetics of removal of carbon dioxide by aqueous 2-amino-2-methyl-1,3-propanediol

Abstract

Kinetics of CO 2 with a sterically hindered amine, 2-amino-2-methyl-1,3-propanediol (AMPD), in aqueous solutions were studied at temperatures of 303, 313, and 318 K and over the concentration ranging from 5 to 25 wt% AMPD using a wetted-wall column absorber. The N 2O analogy was applied to estimate the physicochemical properties such as Henry's law constant and diffusivity of CO 2 in amine solutions. The measured diffusion coefficients of N 2O in aqueous AMPD solutions were correlated using a modified Stokes–Einstein equation. On the basis of the zwitterion mechanism, the zwitterion deprotonation and second-order rate constants were calculated and presented at each experimental condition. The second-order rate constants, k 2, were found to be 382, 665, and 977 m 3 kmol −1 s −1 at 303, 313, and 318 K , respectively. The activation energy for the reaction of CO 2 with AMPD was calculated to be 38.3 kJ mol −1 with an absolute error of 3%.