Kinetics of absorption of carbon dioxide in 2-amino-2-methyl-l-propanol + N-methyldiethanolamine + water

The rate at which CO2 is absorbed in the solvent system 2-amino-2-methyl-l-propanol (AMP) + N-methyldiethanolamine (MDEA) + H2O was determined at 30, 35, and 40 °C in a wetted-wall column. Ten different concentrations of the solvent system were used in which MDEA concentration was varied as 1.0 and 1.5 kmol m−3; that of AMP, as 0.1, 0.2, 0.3, 0.4, and 0.5 kmol m−3. The overall pseudo-first order reaction rate constants for the CO2 absorption estimated from the kinetics data are presented. Data suggest that a small increase in AMP concentration at fixed MDEA concentration in the solvent system will result in significant increase on the rate of CO2 absorption. The absorption was described in terms of a hybrid reaction rate model, which assumed a second-order reaction (CO2 + MDEA) and a zwitterion mechanism for the reaction between CO2 and AMP. The apparent rate constants estimated from the measurements were compared to the corresponding values predicted from the model; the result was satisfactory, with an overall AAD of 4.0%.