Analysis of the energy consumption in solvent regeneration processes using binary amine blends for CO2 capture

Blending two or more amines has recently been recognized as an efficient strategy to formulate competitive sorbents for post-combustion CO2 capture, as it allows to benefit from the advantages of each individual amine. In the present work, we devised four new dual-amine aqueous blends, based on the tertiary amine 2-dimethylamino-2-methyl-1-propanol (2DMA2M1P) mixed with different primary and secondary amines, namely ethanolamine (MEA), benzylamine (BZA), 2-amino-2-methyl-1-propanol (AMP) and diethanolamine (DEA). The CO2 capture and release performance of the formulated blends were experimentally evaluated by measuring CO2 equilibrium solubility, CO2 absorption and desorption rates, and energy consumption during the regeneration process, and results were compared with those obtained under the same operating conditions with 5 M aqueous MEA, the reference sorbent for CO2 capture processes. Moreover, 13C NMR spectroscopy was used to identify and quantify the species formed during the CO2 absorption process to better understand the reaction mechanism in each blend. We found that all formulated blends showed appreciable CO2 capture performance and, most importantly, significantly better desorption performance than conventional MEA. In particular, BZA+2DMA2M1P provided the best capture performance, while AMP+2DMA2M1P showed a faster CO2 desorption rate and lower energy consumption than the other tested blends.