A miniaturised ribbed-rotor Taylor-vortex reactor for low-cost continuous flow enzymatic process development: design, manufacturing, CFD modelling and application in L-m-tyrosine decarboxylation

This work presents the development of a miniaturised Taylor-vortex reactor (mTVR), with volume 2 ml and a sub-mm distance between the rotor and the stator, designed to be easily and cost-effectively manufactured and implemented in enzymatic process development. The rotor contains radial ribs in order to reduce backmixing. A CFD model was used to qualitatively predict hydrodynamic transitions taking place in the annular rib gap, while varying the rotor speed and the volumetric flowrate. A physical prototype was manufactured using 3D printed parts. Macromixing in the 3D printed device was assessed experimentally by residence time distribution (RTD) studies. The mTVR RTD was equivalent to 4–13 CSTRs in series over a wide range of operational conditions, including at low flowrates (space time of > 30 min) where backmixing is often hard to suppress. The effect of operating parameters on experimental RTD curves was correlated with the corresponding simulations. Specifically, the formation of secondary Taylor vortices (in the rib gaps) was shown to affect backmixing. The mTVR was used to produce meta -tyramine via the biocatalytic transformation of meta -tyrosine using tyrosine decarboxylase from Enterococcus faecalis (EfTyrDC). Various operating conditions were investigated using only 0.6 ml of enzyme solution per experimental run. Overall, this work demonstrates the suitability of the mTVR for evaluating the performance of continuous bioconversions using minimal quantities of enzyme and substrate.