Scaling Up Gas–Liquid Photo-Oxidations in Flow Using Rotor-Stator Spinning Disc Reactors and a High-Intensity Light Source

Abstract

Photochemical transformations have garnered renewed interest over the past decade for their ability to enable unique reactions under mild conditions. However, scaling up such processes, particularly in multiphase systems (e.g., gas–liquid), remains challenging. Previously, we demonstrated the potential of the photochemical rotor-stator spinning disc reactor (pRS-SDR) for scaling the photooxidation of α-terpinene to ascaridole, though the system was limited by the light source, resulting in suboptimal operation in a photon-limited regime. In this work, we unlock the full potential of the pRS-SDR by integrating a high-powered light source (up to 652 W optical output) specifically designed for the reactor. The results show that the high gas–liquid mass transfer rates achievable in the pRS-SDR allow for significant productivity improvements under high irradiance (16.3 kg day^–1 at 92% α-terpinene conversion and 2.52 W cm^–2 in a 27 mL irradiated volume), representing an order of magnitude increase compared to our previous study. However, the photooxidation of β-citronellol exhibited notable limitations, highlighting the importance of selecting appropriate model reactions when evaluating intensified photochemical reactors.