Photo-Oxidation in Three-Phase Flow with Continuous Photosensitizer Recycling

The relationship between the three-phaseflow and singletoxygen-sensitized photo-oxidation is unraveled, where sustainabilityis augmented by continuous recycling. Microreactorshave emerged as a promising platform forconductingphoto-oxidations, offering green routes to facilitate significantchemical transformations. In this study, the sustainability of photo-oxidationsis improved by a three-phase gas/liquid/liquid flow reaction in aphoto-microreactor with continuous recycling, which is applied toa model reaction. Recycling is enabled by the photosensitizer andthe substrate, which are in immiscible phases. The effect of variousoperational parameters on the reaction and the contact pattern amongphases is explored, and the interplay between the flow pattern andphoto-oxidation is discussed. The highest conversion is detected forflow conditions that display significantly lower diffusion distancebetween the dispersed photosensitizer slug and the oxygen bubble,highlighting the link between the flow pattern and mass transfer.Furthermore, phase separation was automated using a liquid-liquidseparator where the photosensitizer and organic substrate were recycledcontinuously to achieve full conversion. The proposed approach eliminatesthe downstream purification step and provides a sustainable pathwaytoward photo-oxidations in microreactors.

Automated summary

The relationship between three-phase flow and single-oxygen-sensitized photo-oxidation is explored, with sustainability enhanced by continuous recycling. Microreactors have emerged as a promising platform for conducting photo-oxidations, providing green routes for significant chemical transformations. In this study, the sustainability of photo-oxidations is improved by a three-phase gas/liquid/liquid flow reaction in a photo-microreactor with continuous recycling, applied to a model reaction.