A kinetics study on the absorption of carbon dioxide into a mixed aqueous solution of methyldiethanolamine and piperazine

A kinetics study of the absorption of CO2 into a mixed aqueous solution of methyldiethanolamine (MDEA) and piperazine (PZ) was investigated by a labor atory disk column within 303-343 K and a weight ratio of MDEA to PZ 50/3-50 /10 with a total amine concentration of 3.0 M. A renewal mechanism was prop osed, and a kinetic model was established on the basis of the existence of piperazine carbamate. The second-order rate constant of CO2 with PZ was exp ressed as k(p) = 4 x 10(10) exp(-4059.4/T), which was in good agreement wit h that of Bishnoi and Rochelle (Chem. Eng. Sci. 2000, 55, 5531). The concen trations of various species in solution were also calculated, and the resul ts indicated that the concentration of free PZ was very low for its special reactivity to form the protonated PZ and carbamate in the MDEA solution wh en encountering CO2.