Kinetics of Removal of Carbon Dioxide by Aqueous Solutions of N,N-Diethylethanolamine and Piperazine

N,N-Diethylethanolamine (DEEA) is a very promising absorbent for CO2 removal from gaseous streams, as it can be prepared from renewable resources, Aqueous mixtures of DEEA and piperazine (PZ) are attractive for the enhancement of CO2 capture, due to the high CO2 loading capacity of DEEA and high reactivity of PZ. In the present work, for the first time, the equilibrium and kinetic characteristics of the CO2 reaction with such mixtures were considered. Kinetic data were obtained experimentally, by using a stirred cell reactor. These data were interpreted using a homogeneous activation mechanism, by which the investigated reaction was considered as a reaction between CO2 and DEEA in parallel with the reaction Of CO2 with PZ. It is found that, in the studied range of temperatures, 298-308 K, and overall amine concentrations, 2.1 - 2.5 kmol/m(3), this reaction system belongs to the fast pseudo-first-order reaction regime systems. The second-order rate constant for the CO2 reaction with PZ was determined from the absorption rate measurements in the activated DEEA solutions, and its value at 303 K was found to be 24,450 m(3)/(kmol s).