Optimized ionic liquids for toluene absorption

Abstract

Conductor-like-screening model for real solvents (COSMO-RS) method was used to analyze the solute-solvent interactions and to screen Henry's law constant of toluene over 272 ionic liquids (ILs), to select high-capacity absorbents. Thermogravimetric experiments were carried out to evaluate the toluene absorption by selected ILs at different temperatures and atmospheric pressure. Experimental equilibrium data were found in good agreement with COSMO-RS predictions. Complete desorption of toluene by N2 stripping was achieved, indicating an easy regeneration. The kinetic curves were described by a phenomenological diffusion model, obtaining effective diffusivities in reasonable concordance with those calculated by Wilke-Chang correlation. The separation process with selected ILs was modeled by Aspen Plus and a comparison with organic absorbents was carried out. Equilibrium- and rate-based simulations were used to analyze the importance of thermodynamics and kinetics in toluene absorption by ILs. Current computational-experimental research allowed selecting a set of suitable ILs for toluene absorption. © 2012 American Institute of Chemical Engineers.