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 ( k 0 ) for the homogenous reaction of CO 2 into aqueous solutions of 3-dimethylaminopropylamine (DMAPA) and 3-diethylaminopropylamine (DEAPA) as amine concentrations ranged from 0.05 kmol/m 3 to 0.15 kmol/m 3 and temperature ranged from 293 K to 313 K. It is found that k 0 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 k 2 = 8.69 × 10 9 × exp ( − 4226.2 / T ) ${\text{k}}_2=8.69\times {10}^9\times \exp (-4226.2/\text{T})$ for DMAPA and k 2 = 7.21 × 10 12 × exp ( − 6162.9 / T ) ${\text{k}}_2=7.21\times {10}^{12}\times \exp (-6162.9/\text{T})$ for DEAPA are obtained. The results show that the experimental CO 2 absorption rates exhibited good agreement with predicted CO 2 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 CO 2 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.