Kinetics of CO2 absorption into aqueous solutions of 3-dimethylamino-1-propanol and 1-(2-hydroxyethyl)pyrrolidine in the blend with 3-(methylamino)propylamine

The kinetics of CO2 absorption into unloaded aqueous solutions of 3-dimethylamino-1-propanol (3DMA1P) and 1-(2-hydroxyethyl)pyrrolidine (1-(2HE)PRLD) blended with 3-(methylamino)propylamine (MAPA) were studied in the temperature range of 29–63 °C using a string of discs contactor. In addition, density and viscosity of the blended amines were measured in the temperature range of 25–80 °C, and N2O solubility was measured in the temperature range of 30–90 °C. The obtained results were compared with blends of 2-(diethylamino)ethanol (DEEA) and MAPA. The present study indicated that the blended amines, with varying solvent concentration, obtained comparable values for the overall mass transfer coefficient due to competing effects between solubility, diffusivity and reaction kinetics. The solubility of CO2 was higher in DEEA/MAPA than in the other blended amines, while the calculated values for the pseudo-first order kinetic constant were higher for the 3DMA1P/MAPA and 1-(2HE)PRLD/MAPA solutions than for the DEEA/MAPA solution. The pseudo-first order kinetic constants were correlated to the direct mechanism with reasonable accuracy. The contribution of the tertiary amine as a proton receiver for the MAPA-CO2 reaction represented between 53 and 70% of the pseudo-first order kinetic constant