Reactive-extraction of 2,3-butanediol from fermentation broth by propionaldehyde: Equilibrium and kinetic study

An effective process was developed to separate 2,3-butanediol (2,3-BD) from fermentation broth (FB) by reactive-extraction. Propionaldehyde (PRA) was used as reactant and reaction product 2-ethyl-4,5-dimethyl-1,3-dioxolane (EDD) acted as extractant. HCl was selected as catalyst. Appropriate conditions were obtained by experiment as follows: 10 °C, C _HCl =0.2mol·L^?1, two-stage cross-current extraction, reactant volume ratio (V _PRA : V _FB ) for first stage and second stage is 0.10 and 0.05, respectively. The yield rate of 2,3-butanediol for the whole process can reach 90% w/w, and 2,3-butanediol in the final product can be more than 99% w/w. The novel process required less solution and especially had advantages in treating dilute fermentation broth. Furthermore, equilibrium and kinetic study were investigated on the reaction of propionaldehyde and 2,3-butanediol to provide basic data for process development. The results reveal that reaction enthalpy and activation energy of the reaction were ?21.84±2.38 KJ·mol^?1 and 51.97±2.84 KJ·mol^?1, respectively. Kinetics was well described by pseudo-homogeneous model.