Electrochemical CO2 conversion: upscaling hurdles and perspectives
04-02-2025
Low-temperature electrochemical CO2 conversion is widely recognized as a promising technology for future production of sustainable fuels and chemicals. However, despite rapid growth in research as well as increasing industrial interest, technology development is still at a relatively early stage. Dr. Michele Tedesco, senior scientist Electrochemical Engineering at TNO Rijswijk, sheds his light on the challenges at hand, ranging from catalyst stability to reactor and process design.
Tedesco has over a decade of experience on developing electromembrane processes and electrochemistry topics ranging from electroseparation to flow batteries and electrochemical CO2 capture and conversion. Since 2024, he leads TNO’s efforts in low-temperature CO2 electrolysis, with a special focus on upscaling electrochemical CO2 conversion to ethylene. In June last year, Tedesco took part in organizing a workshop on low-temperature CO2 electrolysis where TNO welcomed nearly 80 experts from industry and academia to discuss the main technical challenges and perspectives. We asked him to summarize a few of the main takeaways.
Enhancing catalyst lifetime
According to Tedesco, the ‘elephant in the room’ is the poor lifetime of the catalysts: “It is the biggest challenge when it comes to scaling up the technology”. This holds especially for copper-based catalysts used for production of C2 products such as alcohols and hydrocarbons. “The state-of-the-art regarding catalyst lifetime is currently some 100 hours, whereas a stability of at least 1,000 hours is required - eventually towards the range of 60,000-90,000 hours. So we really need significant developments here to unlock industrial applications.” He mentions recently proposed approaches to improve catalyst stability based on immobilization of metal nanoparticles into the membrane matrix, via a so-called catalyst-coated membrane approach. “Further research is still needed in this field.”
Accelerating scale-up
The need for improving catalyst stability (and selectivity) means that many (academic) research efforts focus on a fundamental understanding of the electrocatalytic mechanisms affecting catalyst stability. “Such studies are mostly limited to lab-scale cells”, says Tedesco, “with small electrode areas that are typically in the range of a few square centimeters”. He underpins that scale-up and piloting studies are urgently needed so that catalyst lifetime can be evaluated under industrially relevant conditions. Typical features here are electrode areas in the range of a square meter and current densities surpassing 200 mA/cm2. “This will provide the necessary feedback for further catalyst development.”
Improving reactor and process design
The design of many current reactors for CO2 electrolysis is inspired by fuel cells. However, CO2 electrolysis brings its own challenges that need to be addressed. Tedesco: “Take, for instance, gas-diffusion electrodes. These are key to allowing operations at industrially relevant current densities of about 200 mA/cm2. They currently suffer from limited conductivity and risk of ‘flooding’ - which requires careful gas-liquid and pressure management inside the cell. So improvements are really needed here.” Another large field of research focuses on membrane development, he says, with anion-exchange membranes (AEM) currently showing the best performance. “However, the concept of bipolar membranes is also interesting because it offers several advantages such as reduced risk of salt precipitation.” Finally, Tedesco mentions that increasing temperature and pressure of electrolysis cells up to 75° C and 10 bars has been suggested as a promising strategy to decrease cell voltage. “The bottom line is that to bring the technology of electrochemical CO2 conversion to industrial maturity, many innovations are required on reactor design, engineering and operation.”
In June 2024, nearly 80 experts from industry and academia in 8 European countries gathered for an inspiring and interactive workshop at the TNO premises in Rijswijk. The list of speakers included Moritz Schreiber (Total Energies), Remco Hartkamp (Delft University of Technology), Hermenegildo Garcia (ITQ Valencia), Vicente Vert (Matteco), Tom Burdyny (Delft University of Technology), Kai Junge Puring (Fraunhofer UMSICHT), and Mark Sassenburg (TNO). Presentations and recordings of the event are available upon request via info@voltachem.com. For interested readers that are new to the topic, we also suggest to watch the Spotlight Talk organized by TNO for the European Federation of Chemical Engineering (EFCE) on November 6th, with relevant talks from Czaba Janáky (University of Szeged/eChemicles) and Gareth Williams (Johnson Matthey).
Curious to hear more?
Do you have questions about technology development in electrochemical CO2 conversion, or want to discuss aspects mentioned in the article? Please contact us at info@voltachem.com.
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