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Determining photon flux and effective optical path length in intensified flow photoreactors

Nature Chemical Engineering volume 1, pages 462–471 (2024)Cite this article

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Abstract

Photocatalysis for small-molecule activation has advanced considerably over the past decade, yet its scale-up remains challenging in part due to photon attenuation effects. One promising solution lies in combining high photonic intensities with continuous-flow reactor technology, requiring careful understanding of photon transport for successful implementation. Here, to address this, we introduce a characterization approach, starting with radiometric light source analysis, followed by three-dimensional reactor and light source simulation. This strategy, when followed up with chemical actinometry experiments, 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—the effective optical path length. This parameter effectively characterizes photoreactor setups, irrespective of scale, geometry, light intensity or concentration. Additionally, the proposed workflow provides insight into light source positioning and reactor design, and facilitates experiments at lower concentrations, ensuring representative reactor operation. In essence, our approach provides a thorough, efficient and consistent framework for reactor irradiation characterization.

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Fig. 1: Schematic representation of the proposed workflow.
Fig. 2: Overview of the validation of the workflow results using a batch setup.
Fig. 3: Overview of the results for the microcapillary reactor.
Fig. 4: Overview of the results for the pRS-SDR.

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Data availability

The authors declare that all data obtained and used in this work are available within the article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

We express our gratitude to the molecular photonics group (Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam) for using the darkroom and to M. G. Debije (Eindhoven University of Technology) for his assistance with the radiometric measurements. S.D.A.Z., J.H.A.S. and T.N. thank the European Union’s Horizon research and innovation program FlowPhotoChem (S.D.A.Z. and T.N.), grant number 862453 and CATART (J.H.A.S. and T.N.), grant agreement number 101046836. A.C. thanks Janssen Pharmaceutica NV for research funding. C.S. and N.P. thank the Coordination for the Improvement of Higher Education Personnel (CAPES, Brazil, grant number 88887.310560/2018-00) and the National Council for Scientific and Technological Development (CNPq, Brazil, grant numbers 313202/2021-4 and 312247/2022-2) for funding. The materials presented and views expressed here are the responsibility of the author(s) only. The EU Commission takes no responsibility for any use made of the information set out.

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Author notes

  1. These authors contributed equally: Stefan D. A. Zondag, Jasper H. A. Schuurmans, Arnab Chaudhuri.

Authors and Affiliations

  1. Flow Chemistry Group, Van ’t Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Amsterdam, The Netherlands

    Stefan D. A. Zondag, Jasper H. A. Schuurmans & Timothy Noël

  2. Department of Chemical Engineering and Chemistry, Sustainable Process Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands

    Arnab Chaudhuri, Robin P. L. Visser & John van der Schaaf

  3. Department of Chemical and Food Engineering, Federal University of Santa Catarina, Florianópolis, Brazil

    Cíntia Soares & Natan Padoin

  4. Technology and Engineering Group, Janssen Research and Development, Beerse, Belgium

    Koen P. L. Kuijpers & Matthieu Dorbec

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Contributions

S.D.A.Z., J.H.A.S. and A.C. designed the project. S.D.A.Z., J.H.A.S., A.C. and R.P.L.V. performed and analyzed the experiments. S.D.A.Z. performed the ray-tracing simulations, with supervision and input from C.S. and N.P. Additionally, C.S., N.P., K.P.L.K. and M.D. provided input and participated in discussions throughout the course of the project. J.v.d.S. and T.N. directed the project. S.D.A.Z., J.H.A.S. and T.N. wrote the paper with input and feedback from all authors.

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Correspondence to John van der Schaaf or Timothy Noël.

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Extended data

Extended Data Fig. 1 Visualization of the light intensity according to the Bouguer-Lambert-Beer law.

a) Visualization of a photon-efficient system with negligible transmittance. b) Visualization of a non-photon-efficient system with substantial transmittance.

Extended Data Fig. 2 Detailed visualization of the workflow for the batch configuration.

An overview of how the workflow is used to validate the simulated photon flux for the photon-efficient batch configuration. Details on the light source properties and light source model can be found in Section 2 of the Supplementary Information.

Extended Data Fig. 3 Detailed visualization of the workflow for the microcapillary configuration.

An overview of how the workflow is used to determine the effective optical path length through photon flux simulation and chemical actinometry for the microcapillary configuration. Details on the light source properties and light source model can be found in Section 2 of the Supplementary Information.

Extended Data Fig. 4 Detailed visualization of the workflow for the pRS-SDR configuration.

An overview of how the workflow is used to determine the effective optical path length through photon flux simulation and chemical actinometry for the pRS-SDR configuration. Details on the light source properties and light source model can be found in Section 2 of the Supplementary Information.

Supplementary information

Supplementary Information

Supplementary Figs. 1–12, Table 1 and Sections 1–13.

Supplementary Data 1

Statistical source data for Supplementary Figs. 4, 5 and 7–10.

Source data

Source Data Fig. 2

Statistical source data.

Source Data Fig. 3

Statistical source data.

Source Data Fig. 4

Statistical source data.

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Zondag, S.D.A., Schuurmans, J.H.A., Chaudhuri, A. et al. Determining photon flux and effective optical path length in intensified flow photoreactors. Nat Chem Eng 1, 462–471 (2024). https://doi.org/10.1038/s44286-024-00089-3

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