Kinetics of Absorption of Carbon Dioxide into Aqueous Solutions of 2-Amino-2-methyl-l-propanol + Diethanolamine

The specific rate of absorption of CO2 into 2-amino-2-methyl-l-propanol (AMP) + diethanolamine (DEA) + water was investigated at 30, 35, and 40°C using a laboratory wetted-wall column. Eight systems of which 1.0 and 1.5 kmol·m–3 AMP mixed with various DEA concentrations (0.1, 0.2, 0.3, and 0.4 kmol·m–3) were studied. The physical properties such as the densities, viscosities, solubilities and diffusivities of N2O in selected amine systems were also measured. The N2O analogy was applied to estimate the solubilities and diffusivities of CO2 in amine systems. Based on the pseudo-first-order for the CO2 absorption, the overall pseudo first-order reaction rate constants were determined from the kinetic measurements. The addition of small amounts of DEA to AMP results in a significant enhancement of CO2 absorption rates. A hybrid reaction rate model, a second-order reaction for CO2/AMP and a zwitterion mechanism for CO2/DEA was used to model the kinetic data. The overall absolute percentage deviation for the calculation of the apparent rate constant kapp is about 7.2% for the kinetics data measured. The model is satisfactory to represent CO2 absorption rates in aqueous AMP + DEA systems.