Project C19017 | Market: CO₂ Conversion
Written by Yulia Fischer, M2i
January 2026 marked the bold finale of the NWO-funded project TRANSCRIPT. With the successful PhD defenses of Joyce Kromwijk and Angela Melcherts, the final chapters of an ambitious scientific journey were formally closed — not quietly, but with distinction.
TRANSCRIPT — Transforming carbon-rich industrial waste gases of metallurgical plants into valuable products — brought together researchers from Utrecht University and Leiden University under the supervision of Prof. Bert Weckhuysen and Prof. Marc Koper, in close collaboration with Tata Steel. Over the years, the team built a strong international presence, presenting their work at leading conferences and contributing to the growing scientific momentum around CO₂ conversion. But the true achievement of the project lies deeper: it addressed one of the most pressing industrial challenges of our time — how to transform carbon-rich waste gases into valuable chemical building blocks.
Steelmaking remains among the most carbon-intensive industries worldwide. At sites such as Tata Steel, carbon-rich process gases are an intrinsic part of production. Traditionally managed as emissions, these streams increasingly represent opportunity. The question is no longer whether CO₂ should be converted, but how it can be done efficiently, selectively, and under realistic industrial conditions.
TRANSCRIPT approached that question from multiple angles. Instead of focusing on a single reaction pathway, the project built an interconnected research program combining electrochemistry, thermocatalysis, advanced characterization, and reactor development. The result is not one isolated breakthrough, but a coordinated step forward in understanding and control.
A key challenge in electrochemical CO₂ reduction lies in what happens at the electrode surface — an environment that can differ significantly from the bulk electrolyte. Xuan Liu addressed this by developing an in-situ interfacial pH sensor using a rotating ring-disk electrode configuration coupled to a sensitive redox system. As the interfacial environment becomes more alkaline, hydrogen evolution increasingly competes with CO formation. “The interfacial pH is key to unveiling electrolyte effects,” Liu explains. “By tuning the local environment, we can directly influence reaction selectivity.” The work provides industry with actionable insights into electrolyte design and mass transport management.
Temperature and pressure add another dimension. Rafael Vos and Alison Marques da Silva therefore developed a unique high-pressure, high-temperature electrochemical cell — among the first capable of probing CO₂ electroreduction fundamentals under combined elevated conditions. The results were striking. Increasing pressure from 1 to 5 bar significantly enhanced CO selectivity on gold electrodes, raising it from roughly 40% to nearly 90% at constant potential. Increasing temperature alone reduced CO formation, but when pressure was simultaneously elevated, selectivity recovered to around 80%. These findings demonstrate that pressure and temperature effects are strongly coupled. For industrial streams such as those from Tata Steel’s HIsarna process, where CO₂ is emitted at elevated temperatures, such knowledge is essential.
Parallel to the electrochemical work, the project explored thermocatalytic conversion routes. Angela Melcherts investigated Ni/TiO₂ catalysts for CO₂ hydrogenation, focusing on strong metal-support interactions. By varying the reductive pre-treatment temperature, she demonstrated how thin or thick TiOx overlayers form around nickel nanoparticles, fundamentally altering catalytic behavior. Higher-temperature reduction produced a patchy TiOx/Ni interface that enhanced methanation and promoted C–C coupling activity.
In an integrated step, methane produced from CO₂ was further converted into benzene using Mo/ZSM-5 catalysts in a methane dehydroaromatization process. Catalyst deactivation due to coke formation is typically a limiting factor at high temperatures. However, introducing small amounts of CO₂ and H₂ significantly slowed coke growth, allowing operation for 72 hours at 750 °C. The two-stage concept illustrates how CO₂ can move beyond simple molecules and enter higher-value product chains.
Understanding catalytic performance requires more than measuring product streams. Thimo Jacobs developed an analytical toolbox capable of mapping micrometer-scale temperature heterogeneities and reaction intermediates during CO₂ hydrogenation. For the first time, local temperature variations during catalytic CO₂ conversion were visualized at this spatial resolution. Even subtle temperature differences can shift reaction pathways or accelerate deactivation. By making these variations visible, the project strengthened the bridge between laboratory measurements and industrial reactor realities.
For Tata Steel, represented in the project by Jan van der Stel, the relevance is clear. Converting carbon-rich waste gases into valuable products aligns directly with circularity ambitions and long-term decarbonization strategies. The collaboration with academia provided fundamental insights that help evaluate technological feasibility under industrially relevant conditions.
M2i played its role as facilitator and connector, aligning academic depth with industrial urgency. By bringing together expertise in electrochemistry, catalysis, materials characterization, and reactor engineering, the institute ensured that the project addressed both fundamental questions and practical constraints.
TRANSCRIPT does not claim that all challenges in CO₂ conversion are solved. CCU remains an active field of investigation. Mechanistic understanding continues to evolve. Yet what the project has delivered is foundational: validated methodologies, unique experimental platforms, and a deeper understanding of how local environments, temperature, pressure, and catalyst structure jointly determine performance, providing solid steps to making carbon-rich emission gases potential feedstocks.
