Control of Highly Interconnected Reactive Distillation Processes: Purification of Raw Lactic Acid by Esterification and Hydrolysis

Abstract

Plantwide control of processes to purify lactic acid by esterification and subsequent hydrolysis are investigated. Two processes are considered and compared: one using methanol and the other using butanol. The alcohol liberated in the hydrolysis column is recycled to the esterification column, and the water liberated in the esterification column can be re-used in the hydrolysis column, resulting in highly-interconnected process flowsheets. For both processes, designs with one recycle stream (alcohol only) and two recycle streams (alcohol and water) are tested, and for each alcohol and each configuration, both temperature and composition control are tested for all columns (reactive and non-reactive). The results show that processes with only a single recycle stream are somewhat easier to control. For the butanol process, a temperature control structure with only a single composition controller is found to be adequate, while additional composition measurements with constraints on * controller outputs are required for good control of the methanol process. For both processes, responses are more symmetric when temperature control structures are used.

Valorization of Waste Apple Pomace for Production of Platform Biochemicals: A Multi-Objective Optimization Study

“…The resulting lactic acid solution is then vaporized at the temperature of 100 o C to increase lactic acid concentration. Further purification of the lactic acid is achieved via stage-wise processes of esterification, distillation, and hydrolysis [44][45][46]. The process of esterification is achieved using methanol to produce methyl lactate at the temperature of 100 o C and at the pressure of 1 atm followed by the distillation process to remove unreacted methanol components [47].…”

Waste apple pomace conversion to acrylic acid: Economic and environmental assessment

“…This microbe is used in the present study due to its capability to metabolise C5 (~80 % conversion) and C6 (~100 % conversion) sugars to produce LA according to the reactions summarised in Table S3 (supplementary file A). At the conclusion of the fermentation process, the broth is subjected to precipitation treatment followed by acid treatment using Ca(OH)2 at the temperature of 95 o C to facilitate the production of C6H10CaO6 for its separation from the solution [51][52][53]. The C6H10CaO6 is then subjected to acid treatment to enable the recovery of LA, with the waste stream of gypsum generated.…”

“…The C6H10CaO6 is then subjected to acid treatment to enable the recovery of LA, with the waste stream of gypsum generated. Stage-wise separation of the C6H10CaO6 and the gypsum is assumed to be sufficient and is achieved using filtration at 25 o C and 1 atm [51][52][53]. Since the dehydration of the LA to AA requires that the LA stream has a LA content of 50 wt.% [54], a vaporization operation is imposed at the temperature of 100 o C to increase the concentration of LA and achieve 50 wt.% concentration [51][52][53].…”

The conversion of glycerol to methyl lactate catalyzed by tin‐exchanged montmorillonite‐supported gold catalysts

“…However, these reaction systems performed in strongly alkaline media or at high reaction temperatures. In addition, a number of subsequent treatment processes including esterification, distillation and hydrolysis also are required to obtain high‐quality lactic acid and its esters . If the glycerol was oxidized in methanol solvent to directly produce methyl lactate, the aforementioned subsequent treatment processes could be avoided.…”

“…In addition, a number of subsequent treatment processes including esterification, distillation and hydrolysis also are required to obtain high-quality lactic acid and its esters. 19 If the glycerol was oxidized in methanol solvent to directly produce methyl lactate, the aforementioned subsequent treatment processes could be avoided. Moreover, using methanol as a solvent also could avoid the separation of glycerol/methanol, because methanol included in the crude glycerol produced from biodiesel.…”