Intensification of esterification through emulsification: isolation of dilute low molecular weight carboxylic acids

Abstract

A concept for isolation of dilute low molecular weight carboxylic acids, based on surfactant-catalyst enhanced esterification, is proposed.

Reactive Distillation for Solvent Regeneration after Biphasic Carboxylic Acid Esterification

“…To tackle the challenge of carboxylic acid recovery from dilute aqueous streams, a novel process concept based on reactive extraction with esterification and solvent recovery by reactive distillation with transesterification was developed by our group. The esterification‐enhanced reactive extraction step has already been reported by Toth et al 11, 12. The purpose of the present work is to complement the concept by solvent recovery through reactive distillation with transesterification.…”

“…12 In the case of experiments with the catalyst 4‐DBSA, the solvent was made up of a mixture of 1‐octanol and n ‐undecane analogous to the investigation of reactive extraction with emulsion. 11 In a first attempt, the overall process concept was tested by consecutively performing batch reactive liquid‐liquid extraction (bRLLX) and batch reactive distillation (bRD). Therefore, a bRLLX experiment was performed for a reaction time of 4 h at a reaction temperature of 60 °C, a volumetric phase ratio of 1, and an initial acetic acid concentration of 1 mol L −1 in the apparatus described in 11.…”

“…11 In a first attempt, the overall process concept was tested by consecutively performing batch reactive liquid‐liquid extraction (bRLLX) and batch reactive distillation (bRD). Therefore, a bRLLX experiment was performed for a reaction time of 4 h at a reaction temperature of 60 °C, a volumetric phase ratio of 1, and an initial acetic acid concentration of 1 mol L −1 in the apparatus described in 11. It consisted of a 1000‐mL batch reactor stirred with a triple Rushton turbine impeller.…”

“…The esterification step in an emulsified regime has proven feasible with carboxylic acid conversions far beyond the respective equilibrium conversion in the corresponding aqueous feed 11, 12. In this study, 4‐dodecylbenzenesulfonic acid (4‐DBSA) showed high performance in catalysis and emulsification yet opening the challenge of emulsion splitting.…”

“…The high mass transfer area in quasi‐homogeneous (emulsified) state provided by the Brønsted acid surfactant catalyst 4‐DBSA has proven advantageous for high conversion levels. 11 Emulsion handling suggested modification of the catalyst to control its surfactant properties. The modified catalyst proved suitable for the task of providing a quasi‐homogeneous state during extraction without formation of stable emulsions by combining the ion exchange properties of 4‐DBSA with ionic nickel to form the metallosurfactant catalyst Ni(DBSA) 2 .…”