Study of a New Strategy for the Anhydrous Ethanol Production in Units in Rio de Janeiro: Addition of Propylene glycol as Cosolvent

Resumo

The production of anhydrous ethanol, due to the presence of the azeotrope, is difficult using conventional distillation, at pressure atmospheric, as a separation process. One of the methods used is the extractive distillation, consisting in the addition of a third substance capable to change the vapor-liquid equilibrium of the system and obtaining the dehydration of ethanol. Therefore, the ethanol separation process using propylene glycol as solvent was evaluated using the ProSimPlus software. The simulation was done varying the solvent/feed ratios (S/F) in 0.5, 0.7 and 0.9 by weight. The results showed that the azeotrope was broken, obtaining the same ethanol fraction in the three ratios studied. Thus, it was chosen the lower ratio S/F (0.5) to measure the vapor-liquid equilibria of the ternary system, varying the molar concentration from 0.2 to 0.9. The experimental data were measured in triplicate in a similar Othmer's ebuliometer and the analyses of the samples were done in a digital densimeter. The experimental results showed that the azeotrope was broken, validating the results obtained in the simulation, confirming that the propylene glycol is a promising solvent for the production of anhydrous ethanol, and can be applied in the ethanol units present in Rio de Janeiro.