Reaction kinetics of CO2 in aqueous methyldiethanolamine solutions using the stopped-flow technique

Abstract

The kinetics of the reaction between CO 2 and methyldiethanolamine in aqueous solutions have been studied using the stopped-flow technique at 288, 293, 298 and 303 K. The amine concentration ranged from 250 to 875 mol·m -3 . The overall reaction rate constant was found to increase with amine concentration and temperature. The acid base catalysis mechanism was applied to correlate the experimentally determined kinetic data. A good agreement between the second order rate constants for the CO 2 reaction with MDEA computed from the stopped-flow data and the values reported in the literature was obtained.

Determination of Kinetics in Gas-Liquid Reaction Systems. An Overview

“…A typical result of the stopped-flow experiment following the kinetics of CO 2 reaction in aqueous MDEA solution is presented in Figure 7. In this case, the interpretation of the experimental data by a single, pseudo first order kinetics is justified in the narrowed time range, which was explained elsewhere [21]. ) -an example of data treatment [21] A significant limitation of the stopped-flow technique is the possibility of following processes with the overall kinetic rate constant k ov of the order of some hundred reciprocal seconds depending on the dead time of a certain instrument.…”

“…In this case, the interpretation of the experimental data by a single, pseudo first order kinetics is justified in the narrowed time range, which was explained elsewhere [21]. ) -an example of data treatment [21] A significant limitation of the stopped-flow technique is the possibility of following processes with the overall kinetic rate constant k ov of the order of some hundred reciprocal seconds depending on the dead time of a certain instrument. In the best case, monitoring the reaction progress with an observed rate constant close to 1000 s -1 is possible [22].…”

“…Many fast reactions involving ions do not result in measurable changes in absorbance or fluorescence but exhibit a change in conductivity as the reaction proceeds. This is the case of CO 2 /amine/water systems where conductivity detection is typically used to monitor the reaction progress [17][18][19][20][21].…”

“…The whole set-up is schematically illustrated in Figure 6. Details of the experimental conditions and procedure are described in my previous papers [20,21] and therefore only a brief description of the applied methodology will be given here. In a typical run, one syringe contained freshly saturated solution of CO 2 , which was prepared by dissolving a gas in water in a separate reactor under certain pressure.…”

“…The kinetics of the reaction of CO 2 with aqueous MDEA was widely investigated [12,15,21,[24][25][26][27][28][29] using several experimental techniques. Although the kinetic mechanisms for tertiary amines are much simpler than for primary or secondary amines, for which carbamate formation has to be considered, discrepancies have appeared in the literature concerning the reported rate constants which are summarized in Table 2.…”