Synthesis of new amines for enhanced carbon dioxide (CO2) capture performance: The effect of chemical structure on equilibrium solubility, cyclic capacity, kinetics of absorption and regeneration, and heats of absorption and regeneration

Abstract

Abstract This work focused on the synthesis of new tertiary amines by varying the alkyl chain length with/without hydroxyl group in the structure. The effect of chemical structure of newly synthesized tertiary amines; 4-(dimethylamino)-2-butanol (DMAB), 4-(dipropylamino)-2-butanol (DPAB), 4-(dibutylamino)-2-butanol (DBAB), 4-((2-hydroxyethyl)(methyl)amino)-2-butanol (HEMAB) and 4-((2-hydroxyethyl)(ethyl)amino)-2-butanol (HEEAB) were evaluated based on CO 2 equilibrium solubility and cyclic capacity, as well as rates and heats of CO 2 absorption and regeneration. The results showed that three amines (i.e. DMAB, HEMAB and HEEAB) had the highest CO 2 absorption capacity (0.88, 0.44 and 0.68 mol CO 2 /mol amine at 313 K temperature and 15 kPa CO 2 partial pressure), and cyclic capacity (0.52, 0.26 and 0.40 at 313–353 K temperature range, 15 kPa CO 2 partial pressure). These amines also had fast CO 2 absorption rate (0.082, 0.111 and 0.142 mol CO 2 /min) and CO 2 regeneration rate (0.512, 0.452 and 0.295 mol CO 2 /min) while maintaining low heat of CO 2 absorption (−34.17, −56.21 and −69.79 kJ/mol CO 2 ) and heat input of CO 2 regeneration (39.73, 60.48 and 72.44 kJ/mol CO 2 ). Based on these results, DMAB, HEMAB, and HEEAB can be considered to be promising amine components for blending for a post combustion CO 2 capture process.