Acceleration of the reaction of carbon dioxide into aqueous 2-amino-2-hydroxymethyl-1,3-propanediol solutions by piperazine addition

In this work, the kinetics of the reaction between CO2CO2 and piperazine-activated aqueous solutions of a sterically hindered alkanolamine, 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD) was studied in a wetted wall column contactor at 303.15, 313.15 and 323.15 K. The AHPD concentration in the aqueous solutions was kept at 1kmolm-3 while the piperazine (PZ) concentration varied in the range 0.1–0.4kmolm-3. Under pseudo-first-order CO2CO2 absorption conditions, the overall pseudo-first-order rate constants were determined and reaction rate parameters were calculated with a non-linear regression from the overall reaction rate constant. The ratio of the diffusivity and Henry's law constant for CO2CO2 in solutions was estimated by applying the N2ON2O analogy and the Higbie penetration theory, using the physical absorption data of CO2CO2 and N2ON2O in water and of N2ON2O in amine solutions. Piperazine was found to be an effective activator in the aqueous AHPD solutions, as the addition of small amounts of PZ to these solutions has a significant effect on the enhancement of the CO2CO2 absorption rate for all studied temperatures.