The study of kinetics of CO2 absorption into 3-dimethylaminopropylamine and 3-diethylaminopropylamine aqueous solution

In this work, the stopped-flow technique is used to determine the kinetics data in terms of pseudo first-order rate constants (k0) for the homogenous reaction of CO2 into aqueous solutions of 3-dimethylaminopropylamine (DMAPA) and 3-diethylaminopropylamine (DEAPA) as amine concentrations ranged from 0.05 kmol/m3 to 0.15 kmol/m3 and temperature ranged from 293 K to 313 K. It is found that k0 increased with increasing temperature and with increasing amine concentration. The mechanism of the pseudo first-order chemical reaction hypothesis is applied to interpret the experimental data. The Arrhenius expressions as k2=8.69×109×exp(−4226.2/T) for DMAPA and k2=7.21×1012×exp(−6162.9/T) for DEAPA are obtained. The results show that the experimental CO2 absorption rates exhibited good agreement with predicted CO2 absorption rates with an average relative deviation (ARD) of 2.34% and 7.53%, respectively. Finally, the interaction of tertiary amine groups with primary amine groups and the effect of molecular structure on the interaction are discussed by comparing the CO2 absorption and desorption performances in five different systems (MEA, DEEA, MEA + DEEA, DMAPA, DEAPA). It is found that the intermolecular interaction of amino groups is stronger than that of intramolecular interaction.