Absorption of CO2 in amino acid ionic liquid (AAIL) activated MDEA solutions

In order to discover the influence of temperature, solution composition and pressure on CO2 absorption in aqueous solutions of N-methyldiethanolamine (MDEA) and tetramethylammonium glycinate ([N1111][Gly]), this study carried out the equilibrium absorption under a wide range of pressure (0-300 kPa) at three temperatures in a dual-vessel absorption equilibrium system. The impacts of MDEA or IL concentration on the physical properties and absorption performance of CO2 under three temperatures: 25 °C, 35 °C, and 45 °C are compared in five aqueous solutions. It is found that with the increase of IL or MDEA concentration, the solution density grows slightly, while the viscosity rises dramatically. When the equilibrium pressure is less than 60 kPa, CO2 loads increase greatly as the pressure grows while temperature has little influence on the absorption capacities for all the solutions. When the equilibrium pressure is over 100 kPa, the absorption capacity increases gradually as the pressure grows and higher temperature leads to less CO2 load in the solution.