What is it about?
Scientists want to understand how catalysts work while they are actually performing a chemical reaction. Catalysts are materials that help turn simple molecules like carbon dioxide (CO₂) and hydrogen into useful products such as methane, an important energy carrier. In this study, we developed a laboratory setup that allows us to observe catalysts under realistic working conditions, including high temperatures (up to 1000 °C), controlled gas atmospheres, and flowing reactants. Instead of using large synchrotron facilities, which are not always easily accessible, we use a compact laboratory X-ray technique called X-ray absorption spectroscopy (XAS). This method works like an “atomic fingerprint scanner”: it measures how X-rays interact with specific elements in the catalyst, allowing us to track their chemical state over time. In our experiments, we followed nickel nanoparticles during CO₂ methanation. We observed how nickel oxide is transformed into metallic nickel during activation, and how this change is directly linked to the onset of catalytic activity.
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Why is it important?
This work demonstrates that operando X-ray absorption spectroscopy—traditionally limited to large-scale synchrotron facilities—can be performed in a laboratory environment under realistic reaction conditions. The developed setup enables time-resolved measurements on the timescale of minutes, allowing researchers to follow catalyst activation and reaction processes as they happen. A key contribution is the combination of a high-temperature, high-pressure plug-flow reactor with a wavelength-dispersive X-ray spectrometer, together with a careful treatment of experimental limitations such as geometry-induced spectral distortions and temperature-dependent effects. By making operando XAS more accessible, this approach lowers the barrier for studying catalysts under working conditions. This can accelerate research in energy conversion, especially for processes such as CO₂ methanation, where understanding the active state of catalysts is essential for improving efficiency and sustainability.
Perspectives
This work was particularly exciting because it shows how far laboratory-based X-ray spectroscopy has evolved in recent years. Techniques that were once almost exclusively available at large synchrotron facilities can now, at least for certain applications, be implemented in a university lab. A key challenge was not only building the experimental setup, but also understanding and dealing with its limitations—especially effects related to sample geometry and high-temperature measurements. These aspects are often overlooked but are crucial for interpreting the data correctly. From my perspective, the most rewarding part was seeing how structural changes in the catalyst directly correlate with its activity. Being able to observe this connection in a controlled laboratory environment opens up many possibilities for future studies, especially for developing better catalysts for energy-related applications.
Sebastian Praetz
Technische Universitat Berlin
Read the Original
This page is a summary of: Operando
laboratory XAS of Ni nanoparticles in CO
2
methanation using a plug-flow fixed-bed cell with von Hámos spectrometer, Journal of Analytical Atomic Spectrometry, January 2026, Royal Society of Chemistry,
DOI: 10.1039/d6ja00027d.
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