微孔射流毛细管反应器内液-液两相传质和反应选择性

Liquid-liquid biphase mass transfer and reaction selectivity in a micropore-jet capillary reactor

微反应技术在化工过程强化领域已得到广泛应用,尤其适用于快速复杂竞争反应体系。对于液-液两相快速竞争反应,反应过程受传质限制,显著影响反应转化率和收率。本文开发了一种新型的微孔射流毛细管反应器(MJCM),采用微孔射流强化进口处液-液两相传质性能,分别采用水-苯甲酸-煤油体系和水-氢氧化钠-甲苯-苯甲酸-氯乙酸乙酯体系研究了不同操作参数(流量、流量比、表面活性剂浓度、温度)和结构参数(孔径、管长)下液-液两相传质特性和反应选择性,并获得了舍伍德数Sh的关联式。结果表明:随着两相流量的增加,传质效率E呈下降趋势,总体积传质系数k_(L)a呈增加趋势,反应选择性指数Xs则先减小后增大;孔径的增大则会减弱液液传质和反应选择性;随着毛细管长的增加,E和X_(s)逐渐增大,k_(L)a则逐渐减小;水相-有机相流量比的变化对E和k_(L)a会产生不同影响,而温度的适当升高则可以提升反应选择性,表面活性剂的加入降低了传质和反应选择性。与其他液液传质设备对比,MJCM在液-液两相传质、反应选择性方面性能良好,可以用于工业生产进行液液传质与反应过程的强化。

Microreaction technology has been widely used in the field of chemical process intensification,especially for fast and complicated competitive reaction systems.For liquid-liquid biphase fast competitive reactions,the reaction process is controlled by mass transfer property,which significantly affects the reaction conversion and yield.In this paper,a new type of micropore-jet capillary microreactor(MJCM)was developed to intensify liquid-liquid biphase mass transfer property at the inlet.Liquidliquid biphase mass transfer property and reaction selectivity were studied under different experimental conditions(flowrate,flux ratio,surfactant concentration,temperature)and structure parameters(pore size,capillary length),adopting respectively the water-benzoic acid-kerosene system and the water-NaOH-toluene-benzoic acid-ethyl chloroacetate system.Meanwhile,the correlation of Sh was obtained.The results indicated that the mass transfer efficiency(E)decreased,and the overall volumetric mass transfer coefficient(k_(L)a)increased,while reaction selectivity index(X_(s))first decreased then increased,as the flow rates of two immiscible liquid phases were raised.Both liquid-liquid mass transfer and reaction selectivity weaken under larger pore size.Increasing the capillary length resulted in the increase of E and Xs but decrease of k_(L)a.The volumetric flux ratio of the aqueous phase to the organic phase affected E and k_(L)a in different tendency.Moderate rise of temperature can improve the reaction selectivity.Adding the surfactant can decrease mass transfer property and reaction selectivity.Comparing with other liquidliquid mass transfer devices,MJCM showed excellent performance on mass transfer property and reaction selectivity,with promising applications in industrial productions to intensify liquid-liquid mass transfer and reaction processes.