Kinetics of absorption of carbon dioxide into aqueous solutions of 2-amino-2-hydroxymethyl-1,3-propanediol

Abstract

In this work the kinetics of the reaction between CO 2 and a sterically hindered alkanolamine, 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD) were determined at temperatures of 303.15, 313.15 and 323.15 K in a wetted wall column contactor. The AHPD concentration in the aqueous solutions was varied in the range 0.5–2.4 kmol m −3. The ratio of the diffusivity and Henry's law constant for CO 2 in solutions was estimated by applying the N 2O analogy and the Higbie penetration theory, using the physical absorption data of CO 2 and N 2O in water and of N 2O in amine solutions. Based on the pseudo-first-order for the absorption of CO 2, the overall pseudo-first-order rate constants were determined from the kinetics measurements. By considering the zwitterion mechanism for the reaction of CO 2 with AHPD, the zwitterion deprotonation and second-order rate constants were calculated. The second-order rate constant, k 2, was found to be 285, 524, and 1067 m 3 kmol −1 s −1 at 303.15, 313.15, and 323.15 K, respectively.