Amino acid-based ionic liquid as a promising CO2 sorption increasing agent by aqueous MDEA solution

Abstract

The present study aims to enhance the efficiency of CO2 absorption by aqueous MDEA solutions and reduce the energy consumption of the process by designing combined absorbent systems. For this, a novel ionic liquid based on the amino acid glycine, known as bis(2-hydroxyethyl)dimethylammonium glycinate ([M2E2A][Gly]), was synthesized and investigated as a carbon dioxide sorbent. The composition was confirmed using 1H NMR. The sorption capacity of neat [M2E2A][Gly], its aqueous solutions and amine + IL aqueous mixtures was evaluated gravimetrically at different temperatures and concentrations of comprising components. The study observed an increase in both the sorption capacity and the rate of chemical reaction with carbon dioxide when using this compound as an additive. The H2O/MDEA/[M2E2A][Gly] absorbent (50/30/20 wt%) exhibited the highest sorption capacity of 2.98 mol CO2·kg-1solution. Furthermore, a mechanism of CO2 interaction with the H2O/MDEA/[M2E2A][Gly] absorbent was suggested and confirmed using FTIR spectroscopy. To assess the effect of the IL concentration on the absorbent’s viscosity behavior, studying rheological properties of absorbent with different contents of [M2E2A][Gly] were studied.