Experimental Studies on the Effect of Tertiary Amine Promoters in Aqueous Monoethanolamine (MEA) Solutions on the Absorption/Stripping Performances in Post-combustion CO₂ Capture

The absorption/desorption performance of carbon dioxide (CO₂) in aqueous 5 M monoethanolamine (MEA) solutions in the presence of various solution regeneration promoters was comprehensively investigated using a multiple rapid screening method. The promoters considered were N-methyldiethanolamine (MDEA), N,N-dimethylethanolamine (DMEA), N,N-diethylethanolamine (DEEA), 1-dimethylamino-2-propanol (1DMA2P), 1-diethylamino-2-propanol (1DEA2P), 3-dimethylamino-1-propanol (3DMA1P), 2-(dimethylamino)-2-methyl-1-propanol (2DMA2M1P), triethanolamine (TEA), 3-(dimethylamino)-1,2-propanediol (3DMA-1,2-PD), and 3-(diethylamino)-1,2-propanediol (3DEA-1,2-PD). The molar concentration of these promoters added into 5 M MEA was set to 1 mol/L. At the atmospheric pressure, the absorption and stripping experiments were carried out at 313.15 and 353.15 K, respectively. Especially, the CO₂ partial pressure was controlled at constant 15 kPa for absorption experiments. In addition, the equilibrium solubility of CO₂ was also determined in order to evaluate the driving force of each amine system. The results showed that the highest CO₂ equilibrium solubility of 0.5548 mol CO₂/mol amine was obtained by MEA/1DEA2P, whereas both the fastest absorption and regeneration rates were achieved for aqueous blended MEA/1DMA2P solution which made MEA/1DMA2P to exhibit the highest CO₂ cyclic capacity of 1.6710 mol CO₂/L.