(188b) Three Phase Flow and Four Phase Flow in the Taylor Couette Disc Contactor for Combination of Liquid-Liquid Extraction and Chemical Reaction

Production processes of chemicals and drugs typically involve several synthesis steps with phase contact patterns of solids (S) gases (G) and liquids (S). The different phases can act as carrier, reactant, catalyst or solvent. Typically, continuously stirred tank reactors or batch reactors are used for multiphase processes. They are well investigated and adaptable to specific tasks, but also suffer from limited performance. For economic reasons the process design of continuous multiphase processes requires new flexible reactor concepts. The Taylor-Couette Disc Contactor (TCDC) [1] perfectly meets this requirements of intensive multiphase contact up to four phases (GLLS). The design of the TCDC allows continuous mixing and separation of four phases in one apparatus. Three phase operation was successfully validated with heterogeneously catalyzed esterification of acetic acid in aqueous solution with simultaneous extraction of the reaction product into a solvent phase. Simultaneous reaction and liquid-liquid extraction increases the total conversion of acetic acid from 15% (without extraction) to over 30%. The SLL concept may also be applied in hydrometallurgy for leaching combined with solvent extraction, or biotechnological applications. Chemical conversion plus liquid-liquid extraction in the TCDC is best modelled with a tank reactor (CSTR) cascade model. Meanwhile, four phase operation was successfully performed. The hydrodynamics, including dispersed gas phase holdup, solvent phase holdup, the flow regimes as well as axial backmixing and k_La-determination, were investigated and compared with three phase contact hydrodynamics (LLS). The four phase process concept has not yet been confirmed with an appropriate experiment, but it may be useful in heterogeneously catalyzed gas-liquid reactions with phase transfer.

[1] A. Grafschafter, (2019), Simple and Effective: The Taylor-Couette Disc Contactor for liquid-liquid extraction (Design and Performance), Dissertation,