Tuesday, May 3, 2011
Biorefineries use a variety of separation methods in order to produce high value co-products from various feed streams. The ionic liquids represent new classes of non-volatile selective solvents with large solubility as well as low solution viscosities, low toxicity and hazard. These solvents have the advantages of high separation ability, easy operation, and no problem of entrainment of the solvent into the top product of the column. In general, for the solution containing 10–85 wt% ethanol, distillation is effective, while for mixtures containing more than 85 wt% ethanol, conventional distillation becomes ineffective for dehydration, because ethanol forms a minimum boiling azeotrope (95.6% wt% of ethanol at 78.15°C), which makes it impossible to separate ethanol–water in a single distillation column. Bearing this in mind, in this work is proposed an extractive distillation process using ionic liquids which can break the azeotrope formed by ethanol-water. Through rigorous simulation several ionic liquids were tested aiming to improve the properties of separation and lower energy consumption compared to conventional extraction agents, showing significant potential for this application. The ternary vapor liquid equilibrium data was taken from literature and the process was modeled and simulated using ASPEN PLUS® V7.1 simulator.