Regeneration performance of amino acid ionic liquid (AAIL) activated MDEA solutions for CO2 capture

Abstract The regeneration performance of amino acid ionic liquid (AAIL) activated N-methyldiethanolamine (MDEA) solutions was investigated to evaluate the influence of solution composition, regeneration temperature on the regeneration efficiencies and absorption rate of renewed solutions. Three high concentrated aqueous solutions: 15 wt% [N 1111 ][Gly] (tetramethylammonium glycinate) + 30 wt% MDEA, 10 wt% [N 1111 ][Gly] + 30 wt% MDEA and 10 wt% [N 1111 ][Gly] + 40 wt% MDEA were saturated and then regenerated under the regeneration temperature: 363 K, 373 K and 378 K, respectively. The results reveal that most of CO 2 in the liquid phase is released through the thermal regeneration before solution boiling (about 378 K). And higher regeneration temperature causes higher absorption rates of CO 2 in the regeneration solutions, indicating that more [N 1111 ][Gly] can be renewed under higher regeneration temperature. Absorption of CO 2 in the regenerated absorbents over a wide range of equilibrium pressure (0–300 kPa) shows that under the same pressure, the higher regeneration temperature leads to the high CO 2 absorption capacity of the regenerated solutions, and the absorption curves of the solutions regenerated at 378 K are close to those of the fresh solutions, especially when the equilibrium partial pressure of CO 2 is lower than 50 kPa. Considering the regeneration efficiency and absorption rate difference between regenerated solutions and the blank, it can be concluded that MDEA which dominates CO 2 load is fully regenerated, while most IL which determines the absorption rated is renewed.