Purification of Succinic Acid from Synthetic Solution Using Vapor Permeation-Assisted Esterification Coupled with Reactive Distillation

Abstract

In this work, an aqueous solution containing succinic acid, formic acid, acetic acid, and lactic acid with the concentrations of 420, 50, 40, and 10 g.L-1 was employed as the model solution. The solution was pumped into a reactor followed by an addition of the equal volume of anhydrous ethanol. The solution was heated and the esterification reaction was commenced by an introduction of 2% sulfuric acid (w/v). A highly efficient fractionating column designed in our laboratory was employed to shift the conversion beyond the thermodynamic equilibrium conversion by continuous removal of water from the reactor as distillate. In addition, a vapor permeation technique using a commercial hydrophilic polymeric membrane was successfully employed to dehydrate the distillate before returning the dehydrated ethanol into the reactor. This integrated esterification-distillation process allowed a complete conversion of organic acids to the corresponding esters. Due to their much different boiling points, diethyl succinate was completely separated from the other esters by using a vacuum fractionation technique.