Optimization investigation on the novel MEA-MDEA-n-butanol-H2O phase change absorbent for CO2 capture

Chemical absorption has become the most mature and widely used CO 2 capture technology to address CO 2 emissions. Phase change absorbents based on mixed amines combine the advantages of individual amines and reduce regeneration energy consumption. A novel phase change absorbent system based on mixed amine was developed in this study and its CO 2 capture and desorption performance was investigated. The system comprises monoethanolamine (MEA), N-methyldiethanolamine (MDEA), n-butanol and water. Gas-liquid absorption experiments in the microchannel revealed that the flow patterns of the rich phase changed successively through homogeneous flow, irregular droplet flow, tubular-droplet flow and liquid slug flow as the gas-liquid ratio was increased. This transition was influenced by internal circulation, phase change and viscosity, causing the absorption rate to rise initially, then increase slowly before eventually declining. The desorption performance of the saturated rich phase in the MEA-MDEA-n-butanol-H 2 O system was significantly superior to that of the 30 wt% MEA aqueous solution. Comprehensively, the optimal mass ratio of MEA-MDEA-n-butanol-H 2 O was identified as 1.2:1.8:4:3, achieving a higher desorption rate and lower energy consumption. Desorption efficiency and cyclic capacity were 1.8 times those of the 30 wt% MEA aqueous solution, indicating promising application potential.