CO2 equilibrium solubility in and physical properties for monoethanolamine glycinate at low pressures

Abstract

In practical applications, water vapor always coexists with natural gas. As such, the concentration of the ionic liquids (ILs), as promising absorbents for carbon dioxide (CO2) removal, is a crucial parameter sensitively affecting CO2 solubility. In this work, a novel amino acid anion (Glycinate) based IL was synthesized, characterized, and applied for CO2 uptake. Preliminary physicochemical measurements at temperatures of 303–323K showed that increasing the IL purity has adverse effects on density, viscosity, and surface tension of the [MEA][GLY].The impact of the presence of water in the IL samples was also investigated on the CO2 loadings over the temperature ranges of 303–323K and up to a pressure of 600kPa. Among the four aqueous solutions of the IL, the highest CO2 loading of 1.02 (mol CO2/mol IL) was achieved for aqueous IL of 25wt% at an equilibrium pressure of 1.35bar and a temperature of 303.15K. It is found that with increasing equilibrium pressure to about 6.2bar, the loading rate has reached 1.32 (mol CO2/mol IL), which is almost 2.64 times higher than that of the conventional primary amine (0.5mol CO2/mol IL). It is found that although the proposed IL is a promising absorbent for the capture of CO2, highly concentrated of the [MEA][GLY] is not the feasible concentration for CO2 uptake.