Separation Of 1,2,4-butanetriol From Fermentation Broths By Reactive Extraction

1,2,4-Butanetriol(BT)is an important platform chemical which has versatile applications in many fields such as pharmaceutical,military and material industries.Biotechnological route for the production of 1,2,4-butanetriol from renewable materials is expected to replace the traditionally petrochemical way.To date,great achievevement has been made for the biosynthesis and production of 1,2,4-butanetriol.However,its industrialized production is still restricted by the lack of efficient separation technology and related theory for its recovery from fermentation broth.Undoubtedly,the development of highly efficient separation technology for BT is an indispensible step for its extensive application.In this thesis,on the basis of high selectivity of acetalization,a novel process by coupling reactive-extraction and hydrolysis was proposed for the recovery of BT from fermentation broth.Acetalization reaction is the core step of the process described above for the recovery of BT.However,the acetalization of BT has not been reported yet.Therefore,the acetalization reaction between BT and aldehydes(butyaldehyde,valeraldehyde and hexaldehyde)to produce butanetriol acetals(AC)was systemically investigated with different catalyst amount under different conditions of molar ratio and temperature.Through the study of thermodynamic equilibrium,the value of the equilibrium constant as a function of temperature and the corresponding thermodynamic parameters were obtained.Results showed that the reaction in the temperature range of 298-323 K was exothermic and has significantly thermodynamic limitations.A pseudo-homogeneous kinetic model well describing the reaction process was established.The activation energy of the overall acetalization reaction for the tested aldehydes was determined to be in the range of 51.1-52.3 kJ/mol.Furthermore,the effect of alkyl of various aldehydes on acetalization was quantitatively analyzed using linear free energy relationship and it demonstrated that excellent correlation between reaction equilibrium and rate constants and polar effect parameter(?*)was found.Based on above study,a highly integrated separation process by coupling reactive extraction and hydrolysis for recovery BT from fermentation was developed.The key factors such as reactant(extractant),catalyst,phase ratio,reaction temperature and different impurities on the extraction of BT were investigated.Valeraldehyde was selected to react with BT to form acetals which were extracted to the organic phase.Then,the acetals were hydrolysed to BT.The newly developed process was demonstrated to successfully recover BT when using fermentation broth containing 2%(w/w)BT as starting material.The total recovery rate of BT was 84%±5%.In summary,the thermodynamics and kinetics of acetalization had been systematically carried out,based on which a process by combining reactive extraction with hydrolysis for recovery BT from fermentation broths has been sucessfully developed.This research provides valuable data and theory for the industrial production of bio-based BT in future.