Abstract: Microreactors possess advantages such as high heat and mass transfer efficiency, strict control of reaction parameters, ease of scale-up, and good safety performance, and hold promises for enabling and accelerating the discovery of flow chemistry towards highly efficient and more sustainable chemical synthesis. Gas-liquid multiphase catalytic reaction is commonly encountered in chemical production process, where the reaction stream enters the microfluidic channel in a continuous flow and undergoes rapid reaction. The combination of microreactor technology and gas-liquid multiphase catalytic reaction facilitates the development of efficient and sustainable chemical production techniques. Gas-liquid multiphase catalytic microreactors can be classified as wall-coated or filled-bed microreactors based on catalyst fixation approaches. By optimizing the geometric structure design of the microreactor, it is possible to further reduce the reaction time, minimize the material retention and suppress the occurrence of undesirable reactions, thus improving the microreactor performance. However, the optimization of microreactor structure requires a comprehensive understanding of various physics including the flow characteristics of gas-liquid fluids, the mass transfer mechanism and reaction kinetics within the microreactor. Both the flow pattern and mass transfer of multiphase fluids in microreactors will affect the reactor performance. Investigating the gas-liquid system in microreactors promotes improved design of practical devices. This review mainly summarizes typical gas-liquid microreactor examples, and hope to provide inspiration and guidance for the design, fabrication, and application of microreactors. The review is organized as follows, first, the features of microreactor technology are introduced and the optimization strategies for microreactor structures are presented, which is followed by a detailed discussion on the flow patterns, mass transfer characteristics and bubble breakup dynamics in gas-liquid multiphase systems within microreactors. Then, examples of multiphase catalytic microreactors in applications (mainly focusing on wall-coated microreactors and filled-bed microreactors) and their limitations are introduced. Finally, the research trends and application prospects in gas-liquid multiphase microreactors are envisaged.

Key words: microreactor, wall-coated microreactor, filled-bed microreactor, gas-liquid two-phase flow

摘要： 微反应器具有传热传质效率高、反应参数控制严格、易于放大、安全性能好等优势。微反应器技术与气液多相催化反应的结合是开发高效且可持续的化工生产技术重要手段。气液多相催化微反应器集成了催化反应和微反应器技术的优点，在化学合成中具有广泛的应用前景。根据非均相催化剂固定方式，气-液-固三相催化微反应器可以分为壁面负载式微反应器和填充床式微反应器。微反应器中多相流的流动和物质传递都会对微反应器性能产生影响，研究微反应器的气液两相流问题有利于指导高性能微反应器的设计和应用。本工作首先回顾了微反应器技术的特点，介绍了微反应器的结构优化方案，简述了微反应器中的气液两相流流型、传质特点和气泡破裂动力学。随后重点讨论了多相催化微反应器的应用实例以及面临的挑战。最后，结合以往的微反应器研究，对于未来气液两相体系下微反应器技术面临的挑战和发展趋势进行了展望。

关键词: 微反应器, 壁面负载式微反应器, 填充床式微反应器, 气液两相流