Abstract

LED Irradiation as a Scalable Solution for Flow Photochemistry

Oliver Kappe, Professor, Karl Franzens University of Graz

Photochemical transformations are difficult to scale-up due to limited penetration of light. In recent years, it has been shown that continuous flow chemistry can overcome these limitations of photochemical reactions on large scale. Microreactors provide a large surface-area-to-volume ratio, maximizing the exposure of the reaction mixture to light, while ensuring intense and near-uniform irradiation. Moreover, continuous flow operation enables an easy and reliable means of upscaling photochemical reactions. Due to these advantages of flow photochemistry over batch, a large number of photoreactions have been successfully carried out in flow, exhibiting shorter reaction times, better selectivities and enabling larger scale production.

In this lecture, contributions from our research group in the field of continuous flow photochemistry will be highlighted. Emphasis will be given to scalable processes performed in plate-based flow photoreactors of different dimensions (internal volumes) using visible light. The core of these reactors consist of one or more glass-chips with an internal mixing structure for enhanced mass transfer, surrounded by two LED panels positioned either side of the chip. Such systems allow accurate temperature control, using circulation of thermostated fluids, of both the reactor channel and LED panel. The translation from lab-scale to pilot and production scale reactors will be discussed.