Kinetics of absorption of carbon dioxide into solutions of N-methyldiethanolamine+water

Abstract

Kinetics of the absorption of CO 2 into N-methyldiethanolamine (MDEA)+water were investigated at 30, 35, and 40°C using a laboratory wetted wall column. Four systems of which 1.0, 1.5, 2.0, and 2.5 kmol m −3 MDEA aqueous solutions were studied. The solubility and the diffusivity of N 2O in amine systems were also studied. The N 2O analogy was applied to estimate the solubility and the diffusivity of CO 2 in amine systems. Based on the pseudo-first order for the CO 2 absorption, the overall pseudo first-order reaction rate constants were determined from the kinetic measurements. The second-order rate constant of CO 2 with MDEA was found to be as k 2,MDEA/(m 3 kmol −1s −1)=4.01×10 8 exp [−5400/(T/K)]. The activation energy of the reaction of CO 2 with MDEA is found to be 44.9 kJ mol −1. Based on the comparision with liteature values, this model is satisfactory to represent CO 2 absorption rates in MDEA+H 2O for temperatures from 20 to 80°C.