REGENERATION OF IL SOLVENTS USED FOR TERT-BUTYL ALCOHOL-WATER MIXTURE SEPARATION

The present paper discusses the separation of tert-butyl alcohol water mixture in the presence of an ionic liquid and is related to a previous study in which design calculations of extractive distillation and regeneration columns were studied. Separation of an azeotropic mixture was carried out using two ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium bromide ([EMim]Br) and 1-butyl-3-methylimidazoliunn bromide ([BMim]Br), as solvents (heavy entrainers). In the present study, the energy requirements of the extractive distillation processes (including solvent recovery) were studied for both ILs. In previous design calculations, pure solvents (ILs) were considered for extractive distillation. Thus, the regeneration column provided pure ILs, which was reflected also in the higher temperature in the regeneration column reboilers. Experimental measurements of the boiling point temperatures of pure ILs ([EMim]Br and [E[Wim]Br) showed that the regeneration unit temperature in both applied ILs has to be below 245 degrees C. Therefore, ILs regeneration of only 98 % (remaining 2% are water) has been considered in this work. The effect of ILs contamination was monitored in regard to the material balance of the separation and regeneration columns, as well as to the energetic demand of the process considering both ILs.