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

Abstract

The specific rate of absorption of CO 2 into 2-amino-2-methyl-1-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 N 2 O in selected amine systems were also measured. The N 2 O analogy was applied to estimate the solubilities and diffusivities 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 addition of small amounts of DEA to AMP results in a significant enhancement of CO 2 absorption rates. A hybrid reaction rate model, a second-order reaction for CO 2 /AMP and a zwitterion mechanism for CO 2 /DEA was used to model the kinetic data. The overall absolute percentage deviation for the calculation of the apparent rate constant k app is about 7.2% for the kinetics data measured. The model is satisfactory to represent CO 2 absorption rates in aqueous AMP + DEA systems.