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 3M DEEA + 1M 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.