AUTHOR=Mutschler Carole , Aparicio Juliana , Mokbel Ilham , Capron Mickaël , Fongarland Pascal , Araque Marcia , Nikitine Clémence 

TITLE=Reactive Distillation of Glycolic Acid Using Heterogeneous Catalysts: Experimental Studies and Process Simulation

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.909380

DOI=10.3389/fchem.2022.909380

ISSN=2296-2646

ABSTRACT=Glycerol oxidation reaction was developed leading to selective catalysts and optimum conditions for the production of carboxylic acids such as glycolic acid. However, the carboxylic acids are produced in highly diluted mixtures, challenging the recovery and purification, and resulting in high production costs, polymerization and thermal degradation of some of the products.  The protection of the acid function by esterification reaction is one of the most promising alternatives through reactive distillation (RD), this technique allowing simultaneously the recovery of carboxylic acids and the elimination of most part of the water. The reactive distillation, experimental and simulation, of glycolic acid was  performed, based on kinetic and thermodynamics models developed. For the thermodynamic model, binary parameters of the missing couples were determined experimentally, and NRTL model was selected as the most suitable to represent the binary behaviour. The kinetic study of the esterification in the presence of homogeneous and heterogeneous catalysis, concluded, the heterogeneous reaction can be accurately described either by a pseudo-homogeneous model or the Langmuir-Hinshelwood (L-H) adsorption model. Reactive distillation was conducted in a distillation column filled with random packing sulfonated ion-exchange resin, Nafion NR50® or with TiO2-Wox extruded.  The conversion of glycolic acid in reactive distillation increases from 14 % without catalyst to 36 % using TiO2-Wox. As opposed to the batch reactor study, the conversion of glycolic acid was better with TiO2-Wox than with sulfonated ion-exchange resin. The better performance was related to an increase in the hydrodynamics inside the column. Tests using water in the feed confirm the hypothesis by increasing the conversion because of the decrease of the mass transfer resistance.  The simulation of the reactive distillation column with Prosim® plus showed that the yield of the ester increased operating at a low feed rates with reactive stripping. In the presence of water in the feed, non-reactive stages are required, including an enrichment region to separate water vapor.