Measurements and modeling of vapor liquid equilibrium of CO2 in amine activated imidazolium ionic liquid solvents

Abstract

The mean surface temperature has increased considerably over the past few decades primarily due to the huge contribution of CO2, a greenhouse gas. Hence, the reduction of CO2 majorly from the point sources of emission has been a thrust domain of research. This work reports the measurements and modeling of CO2 solubility in newly proposed aqueous solvent blends of 1-butyl-3-methyl-imidazolium acetate ([bmim] [Ac]) and amine activators. Various amine activators viz. 1-(2-aminoethyl) piperazine (AEP) and bis (3-aminopropyl) amine (APA) have been employed in aqueous [bmim] [Ac] over the wide operating temperature and CO2 partial pressure range of (303.15˗323.15) K and (1–390) kPa, respectively. Along with this, qualitative 13C NMR and FTIR analysis have been also performed to assess the proposed reaction scheme. The experimental vapor liquid equilibrium data (VLE) were modeled by modified Kent-Eisenberg equilibrium model including the gas phase non-ideality and Feed forward neural network model. The equilibrium constants associated with [bmim] [Ac], AEP and APA deprotonation, and carbamate formation reactions are regressed to fit the experimental CO2 solubility data. Various important thermophysical properties such as surface tension, viscosity, sound velocity, refractive index and density have also been measured and correlated using established as well as newly proposed models.