Continuous Flow Synthesis of Sodium Tanshinone IIA Sulfonate in Microreactors: Micromixer Design and Process Intensification

This study presents an investigation into the sulfonation of tanshinone II_A, using sulfur trioxide (SO₃) as the sulfonation agent in a microchannel continuous sulfonation system. Key process parameters including pressure, temperature, molar ratio of raw materials, and residence time were examined. After optimization, the sulfonation reaction yield reached 93.2% with a residence time of 5 min and a pressure of 1.5 MPa. To enhance the mass transfer, three types of micromixers were investigated. Computational fluid dynamics (CFD) results showed that the grid-cross-linked micromixer exhibited the highest mixing efficiency at low Reynolds numbers. Finally, by adopting the grid-crossing micromixer to improve mass transfer efficiency, the sulfonation reaction yield reached 90% at atmospheric pressure.