CO2 capture using a functional protic ionic liquid by membrane absorption

An amino acid-functionalized protic ionic liquid (IL), monoethanolamine glycinate ([MEA][GLY]), was used as a CO2 absorbent. Its performance was evaluated by a membrane gas absorption (MGA) process. Various effect factors including both absorbent aspect and operational parameters were investigated in MGA for CO2 capture. Performance of [MEA][GLY] IL was also compared with that of an amino acid salt and an amine. Liquid CO2 loading of the functional protic IL was the largest in three absorbents, presenting an order of [MEA][GLY]>PGLY>MEA. [MEA][GLY] IL obtained a high membrane flux and a low gas outlet CO2 concentration in MGA process. It could reach 3.25 × 10−4 mol m−2 s−1 of membrane flux. The IL could achieve higher initial and instantaneous membrane fluxes and the maximal membrane flux with a range of optimum concentration of 3.5–4.5 mol L−1. Change of operational parameters, especially gas CO2 mole fraction, can significantly affect and enhance the membrane flux of MGA on a limited scale. [MEA][GLY] IL is a more environmentally-friendly and efficient CO2 absorbent.