Influence of cation and anion structure of the ionic liquid on extraction processes based on activity coefficients at infinite dilution. A review

Analysis of cation and anion structure of the ionic liquid and effect of the temperature on the selectivity and the capacity for aliphatics/aromatics and n-hexane/hex-1-ene separation problems was made. Ionic liquids based on imidazolium, pyridinium, pyrrolidinium, sulfonium, phosphonium and ammonium cations were taken into consideration. Analysis was made on the basis on activity coefficients at infinite dilution. All the data were obtained from published literature available at the end of September 2009. It was found that majority of ionic liquids may replace conventional entrainers applied for the separation processes of aliphatic/aromatic hydrocarbons.