Rapid Prototyping for Photochemical Reaction Engineering

Guba, Fabian; Taştan, Ümit; Gugeler, Katrin; Buntrock, Melanie; Rommel, Tobias; Ziegenbalg, Dirk

doi:10.1002/cite.201800035

Cited by 33 publications

(42 citation statements)

References 63 publications

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“…The latter, although often neglected by chemists, is a critical aspect for the outcome of the studied chemical transformation. This includes, for example, the size, shape, and material of the reaction vessel, the characteristics and positioning of the light source(s), and heat-transfer properties, particularly when high-intensity lamps are used [6,7]. The engineering and technological aspects of photochemical processes are often at the basis of the irreproducibility and non-scalability of such transformations.According to the Beer-Lambert law, light transmittance decreases exponentially with the distance from the light source ( Figure 1F).…”

mentioning

confidence: 99%

Flow Photochemistry: Shine Some Light on Those Tubes!

Sambiagio

Noël

2020

Trends in Chemistry

313

223

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Continuous-flow chemistry has recently attracted significant interest from chemists in both academia and industry working in different disciplines and from different backgrounds. Flow methods are now being used in reaction discovery/methodology, in scale-up and production, and for rapid screening and optimization. Photochemical processes are currently an important research field in the scientific community and the recent exploitation of flow methods for these methodologies has made clear the advantages of flow chemistry and its importance in modern chemistry and technology worldwide. This review highlights the most important features of continuous-flow technology applied to photochemical processes and provides a general perspective on this rapidly evolving research field. Microflow Technology and Photochemistry: A Perfect MatchThe use of light to promote chemical reactions has been exploited since the 18th century, but only recently a resurgence has been observed in synthetic organic chemistry, in particular due to the development of visible-light photoredox catalysis [1-5]. All transformations involving light (e.g., Figure 1A-D) must consider, besides classical chemical parameters (i.e., reaction conditions), the photophysical aspects of the sensitizer (see Glossary)/photocatalyst (when used), and the reactor design. The latter, although often neglected by chemists, is a critical aspect for the outcome of the studied chemical transformation. This includes, for example, the size, shape, and material of the reaction vessel, the characteristics and positioning of the light source(s), and heat-transfer properties, particularly when high-intensity lamps are used [6,7]. The engineering and technological aspects of photochemical processes are often at the basis of the irreproducibility and non-scalability of such transformations.According to the Beer-Lambert law, light transmittance decreases exponentially with the distance from the light source ( Figure 1F). For a standard batch reactor (diameter at least in the centimeter range), light intensity decreases considerably from the flask walls to the middle of the reaction mixture, resulting in slow reactions and nonhomogeneous irradiation of the reaction mixture. Performing photochemical reactions in microchannels (ID < 1 mm) allows a higher and more homogeneous photon flux, resulting in shorter reaction times and consequently less side-product formation due to over-irradiation, often observed in batch [8,9]. Another advantage of microflow chemistry, correlated with the large surface:volume ratio, is improved heat and mass transfer, with the possibility to perform mass-transfer-limited multiphasic reactions efficiently [10]. Reactive chemicals and intermediates can be handled more safely in flow than in batch, as no accumulation of dangerous components occurs within the confined reactor volume due to the continuous nature of the process. Together, these result in often faster, safer, and higher-yielding reactions, with the possibility to perform reactions under condition...

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mentioning

confidence: 99%

Flow Photochemistry: Shine Some Light on Those Tubes!

Sambiagio

Noël

2020

Trends in Chemistry

313

223

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“…This demonstrated that it is possible to directly manufacture a photomicroreactor with 3D printing, allowing a high degree of design freedom. The direct manufacturing of a photomicroreactor has also been shown in the research of Guba et al [ 104 ].…”

Section: Reviewmentioning

confidence: 95%

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

Kayahan

Jacobs

Braeken³

et al. 2020

Beilstein J. Org. Chem.

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Photochemical activation routes are gaining the attention of the scientific community since they can offer an alternative to the traditional chemical industry that mainly utilizes thermochemical activation of molecules. Photoreactions are fast and selective, which would potentially reduce the downstream costs significantly if the process is optimized properly. With the transition towards green chemistry, the traditional batch photoreactor operation is becoming abundant in this field. Process intensification efforts led to micro- and mesostructured flow photoreactors. In this work, we are reviewing structured photoreactors by elaborating on the bottleneck of this field: the development of an efficient scale-up strategy. In line with this, micro- and mesostructured bench-scale photoreactors were evaluated based on a new benchmark called photochemical space time yield (mol·day−1·kW−1), which takes into account the energy efficiency of the photoreactors. It was manifested that along with the selection of the photoreactor dimensions and an appropriate light source, optimization of the process conditions, such as the residence time and the concentration of the photoactive molecule is also crucial for an efficient photoreactor operation. In this paper, we are aiming to give a comprehensive understanding for scale-up strategies by benchmarking selected photoreactors and by discussing transport phenomena in several other photoreactors.

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“…This especially holds for the light source. Apart from not reporting important information such as applied optical filters and incident irradiance and the photoreactor itself, information on the geometrical setup of the light source and the reactor are almost entirely missing [99] …”

Section: Challenges Of N2 Activationmentioning

confidence: 99%

Photocatalytic Nitrogen Reduction: Challenging Materials with Reaction Engineering

2021

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Ammonia is not only the most important chemical for fertilizer production, it has also gained much interest as a future hydrogen storage material. Besides the well‐known Haber–Bosch process to generate ammonia from elemental sources, new ways to convert nitrogen into ammonia have been investigated in the last decade for a decentralized production, including electrocatalytic and photocatalytic approaches. However, photocatalysis in particular suffers from stagnating materials development and unstandardized reaction conditions. In this Review, we shine light on recent materials and reaction engineering results for photocatalytic nitrogen reduction, putting an emphasis on the need to connect the activity of reported materials together with detailed reaction conditions and efficiencies. Photocatalytic nitrogen reduction is an emerging field that will certainly gain significant interest in the future as a sustainable pathway to generate green hydrogen and ammonia. The field will certainly strongly benefit from joint efforts with strong interactions between chemists, physicists and chemical engineers at a fundamental level.

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Rapid Prototyping for Photochemical Reaction Engineering

Cited by 33 publications

References 63 publications

Flow Photochemistry: Shine Some Light on Those Tubes!

Flow Photochemistry: Shine Some Light on Those Tubes!

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

Photocatalytic Nitrogen Reduction: Challenging Materials with Reaction Engineering

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