Performance of MAPA promoted tertiary amine systems for CO2 absorption: Influence of alkyl chain length and hydroxyl groups

Abstract

Absorption and desorption of CO2 into five aqueous tertiary amine solvents and their blends with MAPA were studied using a screening apparatus. Results showed that MAPA significantly enhanced both CO2 absorption rate and absorption capacity. The solvent system with the highest CO2 absorption capacity and cyclic CO2 capacity was 3 M DEEA + 1 M MAPA with a CO2 loading of 2.72 mole CO2/kg solution and a cyclic CO2 capacity of 2.06 mole CO2/kg solution. For both the single and the blended systems, the CO2 absorption capacity decreased when increasing the number of ethanolamine groups on the tertiary amine (DEEA → EDEA → TEA) and when the alkyl chain length in the tertiary amine was increased (EDEA → BDEA). When the alkyl amine group in the tertiary amine became hindered (BDEA → t-BDEA), the CO2 absorption capacity increased.