Based upon an in-depth understanding of photon behaviour in photochemical systems, the paper presents an innovative approach to photochemical reactor setup characterization. The workflow starts with radiometric light source analysis and progresses to 3D reactor and light source simulation, coupled with chemical actinometry for photon flux and path length determination.

To showcase its efficacy, the workflow was validated on a batch setup and subsequently applied to two distinct intensified continuous-flow photoreactors: a capillary reactor and a rotor-stator spinning disk reactor. The paper caters to the burgeoning interest in photocatalysis within industrial contexts, and paves the way for seamless scale-ups from lab to pilot and even commercial levels. Furthermore, the nuanced comprehension of the photochemistry process enables a deeper dive into the energy balance of the photochemical reactions, which is a crucial component for future operational expense (OPEX) analyses of the entire process.

The work was carried out in cooperation with researchers at the Sustainable Process Engineering group at Eindhoven University of Technology (TU/e, the Netherlands), the department of Chemical and Food Engineering at the Federal University of Santa Catarina (Florianópolis, Brazil) and the Technology and Engineering Group at Janssen Research and Development (Beerse, Belgium).

Abstract (as published in the paper)

Photocatalysis for small molecule activation has seen significant advancements over the past decade, yet its scale-up remains a challenge due to photon attenuation effects. A promising solution lies in harnessing high photonic intensities paired with continuous-flow reactor technology. However, a deep grasp of photon transport is essential, typically demanding resource-intensive experiments. To address this, we introduce an innovative approach to photochemical reactor setup characterization, starting with radiometric light source analysis and progressing to 3D reactor and light source simulation, coupled with chemical actinometry for photon flux and path length determination. Contrary to conventional techniques that prioritize complete photon absorption, our technique operates optimally when the reaction mixture is unsaturated. This strategy decouples photon flux quantification and path length determination, substantially curtailing the experimental process. The workflow proves versatile across various reactor systems, simplifying intricate light interactions into a single one-dimensional parameter, i.e., the effective optical path length. Combined with the photon flux, this parameter effectively characterizes photochemical setups, irrespective of scale, geometry, light intensity, or concentration. Employing radiometry further offers insights into light source positioning and reactor design, and obviates the need for repeated chemical actinometry measurements due to light source degradation. Additionally, the proposed workflow facilitates experiments at lower concentrations, ensuring representative reactor operation. In essence, our approach provides a thorough, efficient, and consistent framework for reactor irradiation characterization.

Paper details

Stefan D.A. Zondag, Jasper H.A. Schuurmans, Arnab Chaudhuri, Robin P.L. Visser, Cíntia Soares, Natan Padoin, Koen P.L. Kuijpers, Matthieu Dorbec, John van der Schaaf, Timothy Noël: A facile strategy to determine photon flux and effective optical path length in intensified continuous-flow photoreactors. Nat Chem Eng (2024). DOI: 10.1038/s44286-024-00089-3

See also

Research group Flow Chemistry