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.