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

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% [N1111][Gly] (tetramethylammonium glycinate) + 30 wt% MDEA, 10 wt% [N1111][Gly] + 30 wt% MDEA and 10 wt% [N1111][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 CO2 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 CO2 in the regeneration solutions, indicating that more [N1111][Gly] can be renewed under higher regeneration temperature. Absorption of CO2 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 CO2 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 CO2 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 CO2 load is fully regenerated, while most IL which determines the absorption rated is renewed.