Manufacturing chemicals with solar energy and carbon dioxide

FlowPhotoChem is a multi-national, EU-funded research project developing better ways to manufacture chemicals using carbon dioxide (CO2) and sunlight. There is great potential to replace much of the fossil fuels used today to make fuels and useful chemicals by using solar energy and advanced catalysts to convert CO2 into, for example, ethylene, as a precursor for plastics.

FlowPhotoChem (FPC) partners achieved this by combining intensely concentrated sunlight, a modular assembly of three types of flow chemical reactors, new catalysts that are cheaper and more durable than today’s best catalysts, and extensive computer modelling to configure, optimise and manage the reactors. Flow reactors are chemical reactors where the reaction continues on an ongoing basis as raw materials and products flow into and out of the reaction chambers.

The FlowPhotoChem integrated system features a serial arrangement of a photo-electrochemical (PEC), a photocatalytic (PC), and an electrochemical (EC) reactor. The development of the individual reactors was guided from a systems modelling perspective. A system model was created using simplified reactor models. This allowed the team to identify ways to improve solar-to-ethylene efficiency and the production rate at the reactor and system levels.

Experimental results testing the integrated system in the High-Flux Solar Simulator (HFSS) at DLR were used to validate and refine system models, which form a valuable basis for the further development of the modular FPC approach.

Researchers at the DLR Institute of Future Fuels conducted two experimental campaigns in the HFSS, after elaborating suitable irradiation strategies and additional optics for the light-driven reactors, as well as designing an experimental set-up with all components required for flexible and safe operation.

At first, the medium-scale PC reactor from the Polytechnic University of Valencia (UPV) was tested under up to 80 suns, confirming the solar production of carbon monoxide via the reverse water-gas shift reaction. In a second campaign, the integrated FPC system was operated to produce ethylene in a green manner from water, carbon dioxide, and sunlight.

In these tests, the PEC reactor from EPFL/SoHHytec was irradiated using 400-fold concentrated artificial sunlight, whereas an improved PC reactor from UPV (adapted by DLR for pressurised operation) again received up to 80 suns. The electric input for the EC reactor from eChemicles/University of Szeged was assumed to be generated by PV modules.

Based on the experimental campaign results and projected improvements in the integration of reactors, the team estimated the potential to reach a solar-to-ethylene conversion efficiency of 4.4%. When considering other C2+ products such as ethanol, propanol and acetate, the efficiency exceeds 5%, while including all products such as hydrogen and methane, the overall solar-to-chemical efficiency jumps to over 10%.

Exponentially increasing the amount of renewable energy and fuels implemented globally is urgently needed. Access to green and affordable energy is a must in the just energy transition across the globe, and active co-operation programmes between European and African stakeholders can be the clear drivers to support this challenging task.

On 10-11 September in Kampala, Uganda, FlowPhotoChem organised a hybrid workshop to share the modular flow reactor system concept and results and to network with African industrial entities that were in a position to exploit the findings and take the technology forward. More than 100 delegates attended the hybrid meeting hosted by Kyambogo University.

Session facilitators included FlowPhotoChem partners and invited speakers from Africa and Europe. Some showcased successful case studies in the renewable energy and fuels research domains and shared key advantages and challenges encountered during the design and implementation of the case study projects; others demonstrated key outputs from research projects at different stages of technology development and presented opportunities in funding and new ideas for collaboration.

Kyambogo University’s Dr Justus Masa reflected on the benefits of working with FlowPhotoChem. He said: “The support I received enabled us to improve our research infrastructure and the general quality of research provision. Through the collaborations that exist from the consortium, it was made possible to perform experiments we were not previously able to.

“We were also able to establish some lasting collaborations. For example, we signed a memorandum of understanding with the University of Galway to exchange staff and students, as well as to collaborate on research.”

Dr Jelena Stojadinovic, CEO and Founder of MEMBRASENZ, said: “Our collaboration with renowned project partners helped us identify high-performing membrane materials and strategies for new product exploitation.”

Dr Urša Podbevšek, Research Scientist at Johnson-Matthey, also praised the project, stating: “Participating in the FlowPhotoChem project has been very beneficial. It enabled us to assess opportunities in the solar fuels and chemical space. The main technical benefits included developing catalysts and electrodes for the electrochemical reduction of carbon dioxide and carbon monoxide, as well as developing capabilities for testing these materials in electrolysers.”

It’s an exciting time for FlowPhotoChem and its partners. For more information, and to keep up to date with exciting project developments, visit our website.

Please note, this article will also appear in the 20th edition of our quarterly publication.

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