微通道内气液磺化及其传质特性研究

Gas-liquid sulfonation in microchannels and its mass transfer characteristics

以气相SO3作磺化剂,设计了合成十二烷基苯磺酸(DBSA)的气液微磺化系统。依据响应面法分析各因素间交互作用;通过高速摄像机对微通道内伴有磺化反应的气液两相流型进行表征,并测量液膜厚度;通过湍流扩散系数考察湍流对传质的影响,并以此计算液相传质系数和Hatta数。结果表明,微通道内伴有反应气液两相呈带波浪环状流,液膜平均厚度在90~160μm之间;增加液相流量会增大湍流扩散系数,从而增大传质系数。同时,传质系数会随十二烷基苯(DDB)转化率的增加而显著降低,表明随着反应的进行,特别是在反应后期,反应产物将严重阻碍传质过程;此外,Hatta数计算结果表明,其值均大于3,表明微通道中磺化反应仍然是一个快速但受扩散控制的反应。

Gaseous SO3 is used as the sulfonating agent to design a gas-liquid micro-sulfonation system for the synthesis of dodecylbenzene sulfonic acid(DBSA).The interaction between the factors is analyzed according to the response surface method.The gas-liquid two-phase flow pattern accompanied with sulfonation reaction within the microchannel is characterized through a high-speed camera,and the liquid film thickness is also measured.The effect of turbulence on mass transfer is evaluated through turbulent diffusion coefficient,accordingly the liquid-phase mass transfer coefficient and Hatta number are calculated.Results demonstrate that the gas-liquid two-phase flow pattern accompanied with reaction within the microchannel shows a wavy annular flow,with an average liquid film thickness in the range of 90-160μm.The higher liquid-phase flow rate enhances the turbulent diffusion coefficient,thereby increasing the mass transfer coefficient.Concurrently,the mass transfer coefficient will significantly decline as the conversion rate of dodecylbenzene(DDB)increases,suggesting that as the reaction progresses,particularly during the later stages,the reaction products will severely hinder the mass transfer process.Additionally,the calculated Hatta number results indicate that all Hatta values are greater than 3,signifying that the sulfonation reaction within the microchannel remains a rapid,diffusion-controlled reaction.