Biobased entrainer screening for extractive distillation of acetone and diisopropyl ether

This work focuses on the assessment of biobased solvents for the industrial separation of acetone and diisopropyl ether employing extractive distillation. From the experimental screening of 35 (biobased) solvents at 1000 mbar, 84/16 mol ratio acetone/ diisopropyl ether, and a solvent to feed ratio of 1 (mass based) it was observed that DL-limonene entrained diisopropyl ether, resulting in an acetone relative volatility of 1.44. This is a consequence of the selective repulsion of the low-boiling and more polar acetone by DL-limonene. More extensive vapor-liquid equilibrium (VLE) analysis over the entire acetone-diisopropyl ether (pseudo-)binary composition range showed that DL-limonene was the only biobased solvent able to break the azeotrope. The experimentally investigated VLE data of this ternary system was successfully correlated with the NRTL and UNIQUAC models. The other solvents that appeared most interesting in the initial screening were water and ethylene carbonate, entraining acetone with the highest observed diispropyl ether relative volatilities of 2.71 and 11.6. Although the high induced relative volatility for the 84/16 mol ratio acetone/ diisopropyl ether appeared interesting, over the entire composition range this resulted however in a shift in location of the azeotrope rather than removing the azeotrope. Therefore, it was concluded that DL-limonene is for this system the best performing biobased entrainer of the screening study. The observations are in agreement with observations from literature on similar systems, where oxygenated polar solvents were seen to have more affinity towards the ketone than towards the ether, while apolar solvents induce a higher volatility of the ketones.