Opportunities for faster carbon dioxide removal: A kinetic study on the blending of methyl monoethanolamine and morpholine with 2-amino-2-methyl-1-propanol

The effect of mixing 2-amino-2-methyl-1-propanol (AMP) with faster reacting secondary amines (methyl monoethanolamine (MMEA) and morpholine (MORPH)) on the kinetics of the reaction with carbon dioxide in aqueous media has been studied at 298, 303, 308 and 313 K over a range of blend composition and concentration. The direct stopped flow conductimetric method has been used to measure the kinetics of these reactions. The proposed models representing the reaction of CO2 with these blends are found to be satisfactory in determining the overall kinetics of the involved reactions. Blending AMP with either of the amines results in observed pseudo first-order reaction rate constant values (ko) that are greater than the sum of the ko values of the constituent amines. The extent to which the kinetics gets enhanced depends on the temperature and the concentration of each of the amines present in the blend. A linear free energy relationship accounting for steric factors around the nitrogen atom and the pKa of the amine is presented. This relationship satisfactorily correlates the rate constants generated in this work.