Lactic acid recovery using two distillation columns

Abstract

Batch distillation of lactic acid with the simultaneous reactions was studied. The system was equipped with two Oldershaw columns; one was for the esterification reaction and another was for the hydrolysis reaction. Esterification reaction of lactic acid with methanol produced methyl lactate and water. The products of the esterification reaction, methyl lactate and water, were transported to the reboiler of the hydrolysis part. In the reboiler of hydrolysis part, hydrolysis reaction of methyl lactate and water reproduced lactic acid and methanol. Produced methanol in the hydolysis part and unreacted methanol in the esterification part were separated by distillation and recycled to the reboiler of the esterification part and stimulated the esterification reaction. Thus, pure lactic acid solution remained in the reboiler of the hydrolysis part. Two types of strong acid cation exchange resins in the H+ form, DOWEX50W and Amberlyst15Wet, were used as the solid catalyst of this system in order to compare their capacities due to the difference in their structures-gel and macoreticular forms. As a fundamental step of dynamic simulation study for this batch reactive distillation system, a model has been developed in the form of a set of ODEs and algebraic equations.