2,3-丁二醇分离纯化中反应精馏工艺

乙醛-环己烷反应萃取体系能够有效分离发酵液中的2,3-丁二醇。文章重点研究了2,3-丁二醇-乙醛反应萃取液的连续水解精馏工艺,为工业化生产提供理论基础。水解精馏使用阳离子交换树脂HZ732为水解催化剂,以2,4,5-三甲基-1,3-二氧戊环(2,3-丁二醇-乙醛缩醛)水解率为指标,考察了反应段温度、反应段级数、进料速度、进料油水比(2,4,5-三甲基-1,3-二氧戊环和水摩尔比)和回流比的影响。通过实验得到优化水解精馏工艺条件为:反应段平均温度90℃,反应段理论板数为20,进料油水比为0.6,进料速度0.2 h-1。在该条件下2,4,5-三甲基-1,3-二氧戊环水解率为73%,未水解2,4,5-三甲基-1,3-二氧戊环被回收。水解液经精馏得到2,3-丁二醇产品,纯度(质量分数)>96%,总收率≥93%。开发了连续水解精馏工艺,为整个工艺工业化实践提供了参考。

Reactive distillation in 2,3-butanediol separation from fermentation broth

Acetaldehyde-cyclohexane reactive extraction system can effectively separate 2,3-butanediol from fermentation broth.The continuous hydrolyzing process of reactive-extraction liquid was studied.Cationic ion-exchange resin HZ732 was used as catalyst.The hydrolysis rate of 2,4,5-trimethyl-1,3-dioxolane(2,3-butanediol-acetaldehyde-acetal) was used as index.The operation conditions were investigated,which include reaction temperature,reaction stage number,feeding velocity,feed mole ratio of 2,4,5-trimethyl-1,3-dioxolane to water and reflux ratio.The appropriate operation conditions obtained are as follows:reaction temperature is 90 ℃,reaction stages are 20,mole ratio of 2,4,5-trimethyl-1,3-dioxolane to water is 0.6,and feed velocity is 0.2 h-1.Under above conditions,more than 73% of 2,4,5-trimethyl-1,3-dioxolane can be hydrolyzed to form 2,3-butanediol.Finally,distillation was used to purify 2,3-butanediol and recover the unhydrolyzed 2,4,5-trimethyl-1,3-dioxolane.The overall yield of 2,3-butanediol can be ≥93% with purity(mass fraction) of more than 96%.The continuous hydrolyzing process can improve the hydrolysis rate of 2,4,5-trimethyl-1,3-dioxolane and can be used for industrial application.