First generation of translucent monoliths for photochemical applications

Abstract

Monolith structures are a common method to scale flow chemistry tools up to industrial throughput. Internally illuminated monolith reactors (IIMRs) were their versions for photochemistry. The channels inside the monolith were illuminated with optical fibers coated with a photocatalyst such as TiO 2 . The majority of the light in an IIMR was however not utilized to illuminate the reaction medium. Furthermore, the monolith was always made of opaque materials, making it impossible for unabsorbed light to illuminate other channels, lowering the photochemical space-time yield (PSTY), a benchmark for the overall energy efficiency of a photoreactor. In this paper, the potential of a translucent monolith structure for scalable photochemical process design was tested. Due to the translucent nature of the monolith, there was no need for optical fibers or multiple light sources to provide the necessary photon flux and distribution. There has never been a study of translucent monoliths in the open literature and no design parameters have been investigated. This research studies the first translucent monoliths and their design principles by varying the channel size, channel distance as well as the amount of unit cells with a ray tracing algorithm in COMSOL Multiphysics. A model was developed, validated and used to design a monolith for the photodegradation of micropollutants in a case study. A theoretical improvement of seven orders of magnitude in PSTY was obtained compared to IIMRs making this reactor design a promising candidate for more efficient photochemical processes. K E Y W O R D Sadditive manufacturing, COMSOL multiphysics, modeling and simulation, process intensification, ray tracing, translucent monolith

Modeling and Simulation of Reaction Environment in Photoredox Catalysis: A Critical Review

“…It is worth noting that, in addition to CFD-based simulations, some authors are using ray-tracing modeling to visualize photon transport to optimize the design of reactors applied to photochemical reactions (Buglioni et al, 2021). It can be realized using a Monte Carlo ray-trace algorithm from the code development (Zhu et al, 2020) or through the use of commercial software such as LightTools ® (Vishwanathan et al, 2015), Ray Optics Module (an add-on to COMSOL Multiphysics ® ) (Jacobs et al, 2020;Zheng et al, 2020), ANSYS SPEOS ® (Matiazzo et al, 2022), among others. Thus, the use of computational software, whether CFD or based on a ray-tracing algorithm, is essential for the development and improvement of reactors for photochemical reactions where there is a coupling of hydrodynamics, mass transport, and photon transport.…”

Special issue covering the Second International Process Intensification Conference (IPIC2)

“…This novel illumination scheme overcomes the drawbacks of current photochemical reactors as it increases the light efficiency and therefore reactor productivity. In their contribution, Leblebici et al 6 present 3D printed translucent monoliths for photochemical applications, which allows the simultaneous illumination of parallel channels with a single light source. The manuscript discusses the design principles of such translucent monoliths to maximize the overall energy efficiency.…”