Abstract
A wetted-sphere absorber was used to acquire kinetic data for the aqueous phase reaction between CO sub(2) and N-methyldiethanolamine (MDEA). Data were obtained over the temperature range of 293-342 K for partial pressures of CO sub(2) near atmospheric and for 10-30 mass % MDEA. The data are consistent with a mechanism in which MDEA catalyzes the hydrolysis of CO sub(2). Three different mathematical models which are based on Higbie's penetration theory were developed and used to estimate the forward rate coefficient of the MDEA-catalyzed hydrolysis of CO sub(2) reaction. A comparison of the numerical results of the three models indicates that the effect of the reaction between hydroxide and CO sub(2) is significant, especially when estimating the rate coefficient of the CO sub(2)/MDEA reaction for unloaded aqueous MDEA solutions. Neglecting the CO sub(2)/OH super(-) reaction can result in large errors in the rate coefficient for the MDEA-catalyzed hydrolysis reaction, especially at the higher temperatures. The second-order rate coefficients of the MDEA-catalyzed hydrolysis reaction for 10 mass % MDEA, which were estimated according to the most general model, are approximated by the following Arrhenius equation: k sub(21) identical with 2.91 x 10 super(7) exp (-4579/T).