Experimental study of the kinetics of the homogenous reaction of CO2 into a novel aqueous 3-diethylamino-1,2-propanediol solution using the stopped-flow technique

• Kinetics was experimentally studied using the stopped-flow technique.
• Establishing the VLE model and Brønsted relationship.
• DEA-1,2-PD has faster reaction rate than other conditional tertiary amines.
• The mechanism explains the full experimental data.

In this work, the stopped-flow technique was used to determine the kinetic parameters in terms of pseudo first-order rate constants (k0) for homogenous reaction of CO2 into aqueous 3-diethylamino-1,2-propanediol (DEA-1,2-PD) solutions as temperature ranged from 293 to 313 K and amine concentrations ranged from 0.20 kmol/m3 to 1.00 kmol/m3. It was found that k0 increased with increasing amine concentration and temperature. Both the base-catalyzed hydration and the termolecular models were applied to interpret the experimental data. The results showed that the predicted CO2 absorption rates exhibited good agreement with experimental data with an absolute average deviation (AAD) of 5.7% and 3.8% with respect to base-catalyzed hydration and the termolecular model, respectively. Furthermore, the pKa of DEA-1,2-PD was experimentally determined over the temperature range from 298 to 318 K. The relationship between experimentally measured second-order reaction rate constants (k2) and pKa was correlated using the Brønsted relationship. The results suggest that the Brønsted relationship for DEA-1,2-PD developed in this work can predict the reaction rate constant very well with an AAD of 0.8%.