OBTAINING ESTERS FROM DISTILLATED FRACTIONS OF FUSEL OIL: PART II

Abstract

Introduction:
Fusel oil is an impurity in the ethanol production process, from which high value-added products such as esters can be obtained.
Objective:
To experimentally obtain isoamyl acetate by taking advantage of the heavy fraction (>132 oC) separated in the distillation of fusel oil.
Materials and Methods:
The experimental study was carried out in four stages: dehydration of the fusel oil by liquid-liquid extraction with a saturated sodium chloride solution, using anhydrous sodium sulfate as a drying agent; separation of the alcohols present by distillation, esterification and purification of the final product. In the esterification, a PlackettBurman design of experiments was performed analyzing the effect, on the yield, of the variables: feed ratio, reaction time and amount of catalyst.
Results and Discussion:
The water removed represented 24 % of the initial fusel oil sample and upon distillation and characterization by gas chromatography, the working fraction (>132 oC) was found to contain 95.09 % w/w isoamyl alcohol. The highest yield of isoamyl acetate was achieved in experiment IV, when using an acid/alcohol feed ratio of 1.2, 60 min of
reaction and 0.5 % w/w catalyst, obtaining in the purification the ester at 98.01 % w/w.
Conclusions:
The fusel oil used contained ethanol, n-propanol, isobutanol and isoamyl alcohol. The esterification of the heavy fraction, with greater presence of isoamyl alcohol, allowed obtaining its corresponding ester with high levels of purity.