Separating 2,3-butanediol from fermentation broth using n-butylaldehyde

In this paper,a complete separation process for 2,3-butanediol fermentation broth has been developed using reactive-extraction and reactive-distillation. n-butylaldehyde can be used as both reactant and extractant in the process. equilibrium and kinetics were studied on the reaction between 2,3-butanediol and n-butylaldehyde using different catalysts. pseudo-homogeneous model was used to describe the reaction behavior. the kinetic parameters were determined by analyzing experimental data. the results revealed that the reaction enthalpy δrh0 = −21.58 ± 1.63 kj mol−1. the reaction rate was found to increase with increasing reaction temperature and had a linear correlation with catalyst amount. the activity energy for h2so4 system and hcl system was 57.52 ± 5.35 and 58.14 ± 5.06 kj mol−1,respectively. feasible operation conditions have been obtained as follows: volume ratio of n-butylaldehyde to fermentation broth is 0.2; feed molar ratio of water and 2-propyl-4,5-dimethyl-1,3-dioxolane (n-butylaldehyde 2,3-butanediol acetal) for hydrolysis is 3.0; theoretical plate number for reactive-distillation column is 10 with concentration of hcl solution of 0.5 mol/l. with the above conditions,more than 90% of 2,3-butanediol can be recovered from fermentation broth by reactive-extraction process and the purity of final product can be over 99%. © 2013