Scalable Continuous Vortex Reactor for Gram to Kilo Scale for UV and Visible Photochemistry

Abstract

We report the development of a scalable continuous Taylor vortex reactor for both UV and visible photochemistry. This builds on our recent report (Org. Process Res. Dev. 2017, 21, 1042) detailing a new approach to continuous visible photochemistry. Here we expand this by showing that our approach can also be applied to UV photochemistry and that either UV or visible photochemistry can be scaled-up using our design. We have achieved scale-up in productivity of over 300× with a visible light photo-oxidation that requires oxygen gas and 10× with a UV induced [2+2] cycloaddition obtaining scales of up to 7.45 kg day-1 for the latter. Furthermore, we demonstrate that oxygen is efficiently taken up in to the reactions of singlet O2 and, for the examples examined, that near-stoichiometric quantities of oxygen can be used with little loss of reactor productivity. Furthermore, our design should scalable to substantially larger size as well as having the potential for scaling-out with reactors in parallel.

Scalability of photochemical reactions in continuous flow mode

“…Comparison of this methodology to the previously published FEP reactor [9] found the Firefly system to be almost 30% more power efficient which while not crucial on laboratory scale, is of prime importance for manufacturing. The majority of novel innovative reactor designs for kilogram-scale continuous flow photochemical synthesis have only been reported over the last decade [20,61,72,[75][76][77]. Many of these involve scaling up reactors that were designed for laboratory scale synthesis, such as the vortex reactor reported by Poliakoff, George and coworkers [22,76].…”

“…The majority of novel innovative reactor designs for kilogram-scale continuous flow photochemical synthesis have only been reported over the last decade [20,61,72,[75][76][77]. Many of these involve scaling up reactors that were designed for laboratory scale synthesis, such as the vortex reactor reported by Poliakoff, George and coworkers [22,76]. The design of a reactor that utilised a rotating cylinder inside a static cylinder in order to generate Taylor vortices was reported in 2017 [22].…”

Flow Chemistry for Cycloaddition Reactions

“…The inner cylinder is rotated at relatively high speed, generating so called “Taylor” or “Taylor−Couette” vortices, toroidal vortices threaded around the inner rotating cylinder (Scheme ). Scales of up to 7.45 kg per day were obtained with nearly quantitative yields …”

Photon Transport and Hydrodynamics in Gas‐Liquid Flow Part 2: Characterization of Bubbly Flow in an Advanced‐Flow Reactor

“…The scaling strategies included capillaries with a larger diameter, or numbering‐up capillary reactors and structured milli‐scale reactors with integrated static mixers . Most of the scale‐up studies were carried out in a single liquid phase, and as a comparison only few studies looked into scaling gas‐liquid photochemical reactions . When working with a two‐phase flow system, the influence of the flow pattern on photoreactor performance is an aspect that needs to be considered during the scale‐up process, in addition to the light intensity, reagent concentration, and total flow rate.…”