Abstract
Besides the core-equipment design parameters, investment and operational costs of a separation unit are influenced by the down-stream separation apparatuses design. In case of aromatics liquid-phase extraction, down-stream processing is represented by the extraction solvent regeneration carried out in order to obtain pure products, i.e. components of the original mixture, and the solvent that is repeatedly used in the extractor. Solvent regeneration is typically done in a distillation column as the extraction solvent boiling point differs considerably from those of the original mixture components. The presence of a distillation/stripping column and the conditions applied in this equipment show a significant impact on the overall production line profitability. Moreover, purity of regenerated extraction solvents influences the separation efficiency of an extractor. Here, the impact of the extraction solvent nature on the production costs is discussed assuming ionic liquids 1-ethyl-3-methylimidazolium ethylsulfate ([EMim][ESO4]), 1-ethyl- 3-methylimidazolium bis(trifluoromethylsulphonyl)imide ([EMim][NTf2]), 3-methyl-N-butylpyridinium tetracyanoborate ([3-mebupy][B(CN)4)], and 1-ethyl-3-methylpyridinium bis(trifluoromethylsulphonyl)imide ([EMpy][NTf2]), or sulphotane as an extraction solvent used for heptane–toluene mixture separation.
