Simultaneous measurement of CO2 sorption and swelling of phosphate-based ionic liquid

Abstract

The development of alternative CO2 capture solvents such as ionic liquids (ILs) and nanoparticle organic hybrid materials (NOHMs) have provided interesting options for CO2 capture. In this study, CO2 interactions with 1,3-dimethylimidazolium dimethylphosphate ([MMIM]DMP), 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM]DMP) and 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM]DEP) that contain inorganic ester groups based on phosphate, were investigated using ATR FT-IR spectroscopy. CO2-induced swelling, CO2 diffusivity and CO2 capture capacity were simultaneously measured to identify CO2 capture mechanisms, kinetics and diffusion behaviors as a function of the alkyl chain length of the cation. Henry's law constants of CO2 were found to be in the range of 4–11 MPa, which is in agreement with those reported in other studies.