Real-time reaction control for solar production of chemicals under fluctuating irradiance

Zhao, Fang; Cambié, Dario; Hessel, Volker; Debije, Michael G.; Noël, Timothy

doi:10.1039/c8gc00613j

Cited by 43 publications

(50 citation statements)

References 31 publications

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“…To address the issue of variable radiance due to passing clouds, a light sensor was connected to the edge of the LSC plate to measure in real time the amount of light falling onto the reactor. By converting this signal to a certain flow rate, the authors were able to continuously adjust the residence time so that the conversion could be maintained at a constant value during the whole experiment ( Figure 3D) [62]. An improved LSC-PM design with better mechanical, chemical, and photophysical properties was later reported.…”

Section: Solar Photochemistrymentioning

confidence: 99%

Flow Photochemistry: Shine Some Light on Those Tubes!

Sambiagio

Noël

2020

Trends in Chemistry

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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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Section: Solar Photochemistrymentioning

confidence: 99%

Flow Photochemistry: Shine Some Light on Those Tubes!

Sambiagio

Noël

2020

Trends in Chemistry

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313

223

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“…Furthermore, Zhao et al . developed a real‐time reaction control system for their original LSC microreactor, which allows a more or less constant photochemical process under fluctuating solar daylight . The idea behind this approach is the adjustment of the residence time in the reactor to the incident solar light.…”

Section: Reactor Concepts For Flow Photochemistrymentioning

confidence: 99%

Reactor Technology Concepts for Flow Photochemistry

Rehm

2019

ChemPhotoChem

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Synthetic organic photochemistry has been intensively carried out in the 20th century and paved the way to the preparation of complex organic molecules, which were not yet accessible via thermal chemistry. Several photochemical synthesis routes have found their way into industrial applications for the production of everyday commodities, but photochemistry was still underutilized until recently as a synthesis method in organic chemistry. With the advent of novel photocatalytic and photophysical concepts for the use of high power visible light, the research field of synthetic organic photochemistry has evolved to become a vivid and highly recognized technique in the last years. Fortunately, continuous flow technology has also become an increasingly accepted tool and has proved to be an excellent key player for the advancement of photochemistry in academic and industrial research settings. This Review provides an overview on the recent developments of continuous flow photoreactors and their application to photochemical syntheses under mild and defined process conditions.

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“…Based on this key observation, Noël and co-workers rationalized that it would have been possible to acquire accurate information on the instant photon flux reaching the reaction channel by just monitoring the variation in edge emitted photons. Once the relationship between the kinetic profile and the light intensity is known, this information can then be used to compensate the variations in solar irradiance by varying the residence time in the reactor, affording a constant reaction conversion [46]. A simple reaction control system was therefore designed by the same group that updated in real-time the residence time in the reactor by modifying the pump flow rate based on the light intensity measured via a phototransistor placed at the device edge.…”

Section: Reactor Designsmentioning

confidence: 99%

Solar Photochemistry in Flow

Cambié

Noël

2018

Top Curr Chem (Z)

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In recent years, photochemistry has been a highly active research field. This renaissance is linked to the upsurge of photoredox catalysis, a versatile platform for synthetic methodologies using visible light photons as a traceless reagent. In contrast with UV, visible light constitutes almost half of the ground solar irradiance, making the use of solar light in chemistry a sustainable and viable possibility. However, the direct use of sunlight to power chemical reactions is still little explored. This can be explained by both the hurdles associated with solar radiation (e.g., its variability, irreproducibility, high IR content, etc.) and the need for a specialized photoreactor. Most of these issues can be tackled with technological solutions, and especially with the recourse to flow chemistry. Flow chemistry goes hand in hand with photochemistry thanks to the uniform irradiation it provides to the reaction. Furthermore, a continuous-flow reactor can be easily integrated with different solar collectors (including compound parabolic concentrators and luminescent solar concentrators) and constitutes the most efficient approach to solar photochemistry. After a description of the characteristics of the solar radiation relevant to chemistry, this chapter critically describes the different type of solar photoreactors and their applications in synthetic organic chemistry. Finally, an outlook on the future of solar photochemistry in flow is included.

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Real-time reaction control for solar production of chemicals under fluctuating irradiance

Abstract: A simple and inexpensive reaction control system mitigates the impact of solar irradiance fluctuations on the conversion of a sunlight-powered photochemical reaction, affording constant product quality.

Cited by 43 publications

References 31 publications

Flow Photochemistry: Shine Some Light on Those Tubes!

Flow Photochemistry: Shine Some Light on Those Tubes!

Reactor Technology Concepts for Flow Photochemistry

Solar Photochemistry in Flow

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