(488f) Design of Reactive Distillation Process for the Production of n-Butyl Levulinate

Butyl Levulinate (Levulinic acid butyl ester, LABE) is one of the potential fuel additives due to its good characteristics such as high octane number, high oxygen content, and low water solubility. This chemical can be produced by a reversible esterification reaction of n-butanol and levulinic acid (LA). Both raw materials of this reaction can come from bio-conversions. For example, n-butanol can be produced by ABE (Acetone-Butanol-Ethanol) fermentation process, and LA can be produced from lignocellulosics through acid-catalyzed dehydration and hydrolysis of hexose sugars.  

The traditional process for manufacturing LABE requires two-step reaction. First, to convert Levulinic acid to angelica lactone and then followed by reaction of angelica lactone with alcohol. However, the two-step reaction may result in complex process flowsheet and high operating cost. Direct esterification is an alternative way to produce LABE, However, the low equilibrium conversion limitation results in similar complex process flowsheet. This work aims to use reactive distillation (RD) technology to simplify the process by breaking the equilibrium conversion of this reversible reaction.

In the RD process, high-purity LABE is designed as bottom product while top vapor approaching the minimum-boiling azeotrope of n-butanol and water. With top vapor condensed in a decanter and an additional flash drum, high-purity water product at 99.9 mol% can be withdrawn from the liquid draw of the flash drum. The vapor stream of the flash drum is condensed and recycled back to the decanter. Aspen plus simulation shows that an economical design flowsheet with high overall conversion of 99.5% can be achieved with stoichiometric feed of two reactants in the proposed RD process.