Periodic Reporting for period 2 - reaCtor (Fibre-based plasmonic micro reactor for flow chemistry)
Periodo di rendicontazione: 2024-04-01 al 2025-09-30
Major challenges of the European society such as the climate crisis, insufficient environmental protection, pharmaceutical shortages, and military aggressions require solutions that substitute fossil fuels by sustainable energy sources and significantly reduce energy consumption in basically all industries. Following the green deal of the EU commission, the European continent shall become the first climate-neutral continent by 2050. Particularly, the chemical industry is a major contributor to CO2 emissions as it accounts for about 30 % of industrys’ total energy use worldwide. As a consequence, disruptive new technologies must be developed to reduce greenhouse gas emissions.
It is widely agreed that photochemistry in flow reactors is an eco-friendly and safe technology for the synthesis of useful compounds and further applications such as water treatment. Compared to batch reactors, flow photochemistry benefits significantly from continuous flow due to improved reaction selectivity, irradiation conditions, mass and heat exchange, and operation safety. However, despite the overwhelming advantages of microreactor flow photochemistry, the technique has not been widely adopted by the chemical industry, so far. A major bottleneck is the missing light management inside the microflow reactors, which significantly hinders its upscaling and large-scale application in industry. This is exactly where the key to the technological and economic breakthrough lies, and this is where reaCtor comes into play by offering an innovative solution, which allows for decoupling the light excitation from the reaction fluid. By integrating a chemical reactor inside a specialty optical glass fiber, inside which light is further redistributed through plasmonic nanoparticles, our approach allows for unprecedented levels of light management, full excitation wavelength tunability and industry demanded scale-up.
To reach this ambitious goal, the interdisciplinary reaCtor consortium works on several objectives: A novel microreactor fiber for high efficiency interaction with the reaction volume is designed, fabricated, and validated. In addition, for efficient and robust optofluidic interfacing, two concepts are under development: a novel monolithic fiber component and laser-based micro-machining process. For enhanced reactant excitation and flow photochemical reaction yield, plasmonic nanoparticles are designed and will be implemented in the microreactor fiber. The final outcome of reaCtor will be a demonstrator of the proposed microreactor, which will be validated and benchmarked with respect to a number of photochemical reactions. The technical work is accompanied by a strong dissemination and communication strategy to engage relevant stakeholders.
It is widely agreed that photochemistry in flow reactors is an eco-friendly and safe technology for the synthesis of useful compounds and further applications such as water treatment. Compared to batch reactors, flow photochemistry benefits significantly from continuous flow due to improved reaction selectivity, irradiation conditions, mass and heat exchange, and operation safety. However, despite the overwhelming advantages of microreactor flow photochemistry, the technique has not been widely adopted by the chemical industry, so far. A major bottleneck is the missing light management inside the microflow reactors, which significantly hinders its upscaling and large-scale application in industry. This is exactly where the key to the technological and economic breakthrough lies, and this is where reaCtor comes into play by offering an innovative solution, which allows for decoupling the light excitation from the reaction fluid. By integrating a chemical reactor inside a specialty optical glass fiber, inside which light is further redistributed through plasmonic nanoparticles, our approach allows for unprecedented levels of light management, full excitation wavelength tunability and industry demanded scale-up.
To reach this ambitious goal, the interdisciplinary reaCtor consortium works on several objectives: A novel microreactor fiber for high efficiency interaction with the reaction volume is designed, fabricated, and validated. In addition, for efficient and robust optofluidic interfacing, two concepts are under development: a novel monolithic fiber component and laser-based micro-machining process. For enhanced reactant excitation and flow photochemical reaction yield, plasmonic nanoparticles are designed and will be implemented in the microreactor fiber. The final outcome of reaCtor will be a demonstrator of the proposed microreactor, which will be validated and benchmarked with respect to a number of photochemical reactions. The technical work is accompanied by a strong dissemination and communication strategy to engage relevant stakeholders.
Within the second report period, lasting from May 2024 to September 2025, the reaCtor consortium has made significant progress by extending the initial work of the first report period. The numerical and theoretical design of the fibre was finalized. Meanwhile, the fabrication of the fibre preform on one side and the fiber drawing on the other side has been optimized iteratively. Current fibers feature losses as low as 1-3 dB/m in the relevant wavelength regime. In parallel, the reactor consortium worked on the fluidic and optical interfacing. For the latter, it became evident that the originally foreseen concept, i.e. a nanostructured beam converter, cannot obtain the desired efficiency of the light in-coupling. Thus, in accordance with a proper risk management, the consortium started to work on two alternative concepts. In particular, the fs-laser based inscription process for the microfluidic functionalization is now also used to inscribe waveguides in bulk glass material, which will be part of the optical interfacing. The alternative light in-coupling approaches will also feature an enhanced fluidic interfacing through the facets of the fibre. Nevertheless, the consortium also continued their work on the lateral fluidic interfacing and, for example, showed that sufficiently small in-/outlets do not critically affect the waveguiding of the fibre. In parallel, the theoretical understanding of the flow chemistry within the fibre has been refined and important benchmark parameters such as the volume flow rate have been studied theoretically, providing a guideline for further developments. Significant progress was also made towards the nanoplasmonic functionalization of the reactor fiber. By adapting a corresponding protocol developed for fibre-mimicked glass substrates, fibers were successfully functionalized with plasmonic nanoparticles as confirmed by spectral absorbance measurements. Most importantly, the consortium agreed on a first benchmark reaction, namely the generation of singlet oxygen. In a corresponding experiment with a functionalized glass substrates, feasibility to actually drive the corresponding reaction with a corresponding laser source was confirmed. Intital plannings were already made to adapt these measurments towards the fibre-based demonstrator that will be realized in the final report period.
In addition to the technical work, the consortium communicated and disseminated the project and its results via various channels such as scientific conferences and industrial fair trades. Disucssions with potential end-users were initiated and provided valuable feedback towards the planned benchmarking and the following dissemination of our technology.
In addition to the technical work, the consortium communicated and disseminated the project and its results via various channels such as scientific conferences and industrial fair trades. Disucssions with potential end-users were initiated and provided valuable feedback towards the planned benchmarking and the following dissemination of our technology.
In particular, the successful realization of the envisoned specialty fibre in combination with (i) its fs-laser based fluidic functionalization and (ii) the nanoplasmonic functionalization goes significantly beyond the technical state of the art. Besides, the gained theoretical understanding of the flow and reaction conditions within the fibre-based reactor is novel and helpful for the further realization of the demonstrator. The consortium still plans to realize the final demonstrator as rugged and monolithic as possible, followed by an in-depth assessment and benchmarking towards relevant applications. We believe that our technology offers unique selling points for the later dissemination, in particular a near-unity control of the photon interaction while using coherent (narrowband) laser sources that can even be multiplex for significantly enhanced selectivity or monitoring. The selected singlet oxygen generation as a first benchmarking experiment is highly relevant towards various applications such as the synthesis of therapeutically relevant compounds or fragrances.