微型反应器
光催化
硝基苯
间歇式反应器
体积流量
催化作用
反应速率
化学工程
材料科学
化学
惰性气体
有机化学
复合材料
量子力学
物理
工程类
作者
Yuhang Chen,Yaheng Zhang,Hao Zou,Minglei Li,Gang Wang,Min Peng,Jie Zhang,Zhiyong Tang
标识
DOI:10.1016/j.cej.2021.130226
摘要
Difficult handling the solid catalysts remains one of the pain points in the continuous flow photochemistry. In this work, the gas–liquid-solid segmented flow was employed in the photocatalytic production of azo- compounds (azoxybenzene and azobenzene) from nitrobenzene using graphitic carbon nitride (g-C3N4) as solid catalyst. Compared with the batch reactor, the photocatalytic reaction rate was greatly improved in the microreactor, and the reaction time was shortened from 180 min of the batch to 7.5 min for near-full conversion of nitrobenzene. The effects of various reaction parameters (temperature, light source power, catalyst content) in the continuous system were examined, and the reaction kinetic was found in first order. The photocatalytic reaction performance was very sensitive to the gas–liquid-solid segmented flow conditions, which needed to be carefully tuned. With the help of high-speed camera and micro particle image velocimetry (µ-PIV) techniques, it was identified that the increasing inert gas fraction resulted in more stable segmented flow with shorter liquid segments, favoring the reaction rate. With a high gas fraction, the intensity of recirculation in the liquid segments was strengthened by the increasing total flow rate, enhancing the local mass transfer, thereby benefiting the photocatalytic reaction. Overall, the continuous microreactor reached 5.6 times higher productivity per volume (26.1 mmol/h*L) of azo- compounds than the batch reactor under the same conditions. The successful photosynthesis of azo- compounds demonstrated the great potential of the presented gas–liquid-solid segmented flow, and the findings of this work provide useful guidance on its future application in other heterogeneously catalyzed reactions.
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