(27d) Multiphase Operations in the Taylor-Couette Disc Contactor

The majority of chemical reaction steps or separation steps require two or more phases, including contact of solids (s), liquids (l) and gases (g). The phase system needed for a specific process step defines the equipment design. In literature, several reactors are recommended, depending on the phase contact and mechanism [1]. However, flexibility of equipment may be limited by the design for case specific applications. This study is focused on flexible continuous multiphase applications of the Taylor Couette Disc Contactor (TCDC) [2], a column type stirred contactor. The high potential of the TCDC in multiphase applications was investigated. It will be demonstrated with two different applications in lab scale.

Continuous in-situ extraction of methyl acetate from heterogeneously catalyzed conversion was performed in the TCDC. For this experiments an aqueous mixture of acetic acid was esterified with methanol at 65°C and the heterogeneous catalyst Amberlyst 15. Continuous counter current extraction of the reaction product shifts the unfavorable reaction equilibrium of this esterification reaction to the product side. The overall equilibrium conversion was increased from 20% without extraction to 30% with simultaneous solvent extraction of the ester with ShellSol T.

The same apparatus was used for the continuous synthesis of 2-Methoxyhydroquinone (MHQ) from Vanillin according to [3]. MHQ is a bio-based electrolyte for aqueous redox flow batteries This reaction results in phase separation, with the product accumulating in the light tetrahydrofuran solvent phase. MHQ synthesis was performed in the TCDC in co-current operation mode with phase separation at the top of the apparatus. Side reactions of MHQ synthesis lead to CO₂ formation. The gaseous CO₂ can easily leave the column at the top. High selective conversion of 80% was achieved in continuous operation. These two different applications of the TCDC demonstrate the high flexibility and performance of this multipurpose apparatus concept.