The Interplay of Irradiated- and Shaded Zones in Photoreac-tor Scale-Up

Despite the potential benefits of using light to drive chemical reactions, photoreactions are rarely implemented on an industrial scale. One of the main issues is the challenging scale-up due to the exponential light attenuation with increasing optical pathlength. Therefore, shaded zones within the reactor can exist at positions far from the light source with few available photons and thus low reactivity. To analyze the impact of light attenuation and to optimize the reaction conditions during scale-up, a compartment model is presented and benchmarked with a photooxidation reaction in a Taylor-flow capillary reactor. The simulation results highlight that a thorough optimization of light intensity and photosensitizer concentration, as well as an enhanced mixing of the liquid phase, are required to minimize the reaction-inhibiting effect of light attenuation and to enable a high reactor performance, especially during scale-up.