Simulation of a new regeneration process of solvents with ionic liquid by short-path distillation

Abstract

A new promising process for the regeneration of solvents with ionic liquid (IL) by short-path distillation (SPD) has been proposed and its application potential analyzed by simulation. Main advantage of this process compared to classical stripping with alkali solution is that the product is in form of free acid, not its salt and the consumption of chemicals is reduced. The model loaded solvent with phosphonium IL from membrane based solvent extraction (MBSE) of butyric acid (BA) was regenerated by two stage SPD at the temperature of 130 and 160°C and pressure of 13 and 2kPa, respectively. SPD was combined with extraction of BA from the dodecane phase of distillates by water. Yield of BA in distillates was 89%. The concentration factors of BA in both concentrates compared to BA concentration in the fermentation broth were of 25 and 43, respectively, for the dodecane content in the dry solvent containing 70 mass% of IL. Overall theoretical heat consumption in SPD was 3410kJperkg of recovered BA. The simulation has shown that both the yield of BA in MBSE and the mass flux of the solvent in MBSE are strongly influenced by the residual content of BA in recycled dodecane after the extraction of BA. Both parameters play a key role in the process performance. Additional experimental data on MBSE, SPD and dodecane extraction are needed for design and optimization of the hybrid process.