Title : Catalysis in segmented flow from lab scale to production
Abstract:
Flow chemistry is a rapidly developing technology that enables batch-to-continuous synthesis from the lab scale to industrial production. Monophasic flow, including liquid flow through a fixed bed of solid (cartridge), is the dominating contacting motion since most of the chemistry is monophasic, or performed with a solid which in general is the catalyst. However, segmented flow – also called Taylor flow – is largely used when two fluid phases – one phase being a liquid, the other being either a gas or a liquid – are used. Segmented flow develops as a train of bubbles (droplets) in a continuous liquid phase when the size of the bubbles (droplets) is close or larger than the diameter of the reactor. Thus, segmented flow could typically be observed in small tubes or capillaries found in many flow chemistry equipment’s such as those commercialized by Syrris, Vapourtech, Kobelco to name a few. The very specific fluid motions of Taylor flow lead to very efficient properties such as mixing and mass and heat transfer. Furthermore, more than two fluid phases could be contacted and solids could also be transported at quite high loadings. Such versatility opens the field to many applications in catalysis and material synthesis. During the lecture, beside the basic hydrodynamic properties of segmented flow, many possible utilisation of segmented flow for performing catalysis and material synthesis will be presented in particular solutions to use solids and gas-liquid or liquid-liquid mixtures. Examples were solid catalysts are transported as slurry for hydrogenation reactions, or examples were segmented flow is combined with the properties of Open Cell Foams (OCF) as catalyst supports for the very exothermic hydrogenation of terpenes will be presented. Very exothermic and fast O2 oxidations of organics are also performed in segmented flow with scale-up example to several kg. Last, the synthesis of metallic nanoparticles of Ru and RuCu without ligands and with very interesting size and size distribution could also be performed in hydrogen-ionic liquids segmented flow. Finally, segmented flow could also be used to operate several cascades catalysis using the droplets as milli-reactors.
