Using [EMIM][OAC] as entrainer for isopropyl alcohol dehydration via extractive distillation

Abstract

Recently, many researchers focus on the applications of ionic liquids (ILs) because they are almost non-volatile, thus appear to be easily separated. One of the applications is that ionic liquids can be used as entrainer in extractive distillation. This work designs an extractive distillation system using ionic liquids as entrainer for isopropyl alcohol (IPA) dehydration. First, a way to build thermodynamic models of ionic liquids is proposed. Second, the entrainer recovery with two-flashers and flasher-stripper configurations using IL as entrainer are discussed. Finally, the process using 1-ethyl-3-methylimidazolium acetate ([EMIM][OAC]) as entrainer is compared with the one using dimethyl sulfoxide (DMSO) as entrainer under two IPA purity specifications. The total annual cost (TAC) of the two recovery configurations using [EMIM][OAC] under higher IPA purity specification are both higher in comparison with the conventional designs. On the other hand, the TAC of the IL process with lower IPA purity specification with two-flashers and flasher-stripper configurations are 7.19% and 8.34% lower in comparison with the conventional designs. This case study indicates that the favorable properties of ionic liquid as entrainer are to greatly enhance relative volatility of the mixture going to be separated and to have better thermal stability.