Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Extractive distillation processes with and without salt have been proposed to produce anhydrous ethanol. For the feasible use of anhydrous ethanol for blending in gasoline, the energy required to produce anhydrous ethanol must be less than the energy generated by its combustion. The energy required to produce anhydrous ethanol by extractive distillation with ethylene glycol is approximately 19 MJ*kg-1, whereas it lies in the range of (5.02 to 9.27) MJ*kg-1 for extractive distillation with salt. Thus, the energy requirement in extractive distillation with salt is reduced. However, the use of nonvolatile salts involves problems encountered in its dissolution and subsequent crystallization. It is desired to make efforts to explore organic compounds to be used as an extracting agent in the production of anhydrous ethanol that could be consumed within the process or could be recovered with least capital/energy inputs. In view of the above, diaminomethanal (commonly known as urea) has been identified, and its effect on the vapor-liquid equilibria (VLE) of the ethanol + water system at atmospheric pressure has been studied using the Othmer type recirculation still. The relative volatility of the ethanol + water solution is found to increase monotonically with the increment of diaminomethanal up to 4.16 kmol*m-3. It is also found that the azeotrope formation in the ethanol + water system is completely eliminated with diaminomethanal at concentrations equal or higher than 2.26 kmol*m-3.