A Novel Nebulizer‐Based Continuous Flow Reactor: Introducing the Use of Pneumatically Generated Aerosols for Highly Productive Photooxidations

Abstract

Abstract:A very effective and highly innovative continuous flow reactor (CFR) for undertaking important large scale photooxidations is presented. Until now, two major issues have obstructed the widespread use of photooxidation CFRs; both problems are nullified by this novel and yet extremely simple reactor design. The first issue related to the detrimental effect of poor oxygen solubility on the rate of the biphasic gas-liquid reactions and the second was the rapid attenuation of light by solutions which severely limited dimension enlarging opportunities. The new and easy to operate reactor works by nebulizing a photooxidation solution inside a cylindrical chamber surrounded by a low energy LED strip; thus, the interfacial area between the two phases is maximized, leading to greatly improved reaction rates and excellent light penetration. This pneumatic nebulizer-based photooxygenation system (NebPhotOX) can use air (as the oxygen source) and very concentrated photooxidation solutions. NebPhotOX has very high productivity and could potentially be scaled up easily to work in an industrial setting.

Continuous Flow Photochemistry for the Preparation of Bioactive Molecules

“…Another approach to realize such photooxygenation reactions in a continuous manner was reported by Pergantis and Vassilikogiannakis, who developed a nebulizer-based photo-reactor [27]. Therein, an aerosol is generated and sprayed into an irradiated reaction chamber by mixing a stream of air or oxygen with the substrate solution.…”

Process Intensification – An Unbroken Trend in Chemical Engineering

“…Further process intensification can be achieved through continuous flow reactors . Furthermore, several recent publications illustrate the benefits of advanced reactor concepts, e.g., packed‐bed‐, pneumatic nebulizer‐, slug flow, annular flow, vortex or luminescent solar concentrator reactors .…”

Regioselective Photooxidation of Citronellol: A Way to Monomers for Functionalized Bio-Polyesters

“…Due to the instability of the hydroxyperoxides 2 and 3, the corresponding alcohols 4 and 5 are isolated after in situ reduction of the reaction mixture (Scheme 1). Recently, the process has been implemented thanks to the use flow methods (Maurya et al, 2011;Park et al, 2015;Clark et al, 2016;Ioannou et al, 2017;Anselmo et al, 2019), achieving increased efficiency compared to the batch conditions. However, the potential synthetic use of this reaction is suppressed by its poor selectivity, whereas in all cases a mixture of secondary and tertiary alcohols 4 and 5 is obtained in almost equimolar ratio (Maurya et al, 2011;Park et al, 2015;Clark et al, 2016;Ioannou et al, 2017).…”