Catalysts drive billions of dollars in industrial chemical production – but their inner workings are often hidden from view. Now, scientists have captured unprecedented atomic-level footage of methane converting into synthesis gas on palladium catalysts under realistic working conditions. The findings reveal that the most effective catalysis happens at the shifting boundary between metallic palladium and palladium oxide – offering rare visual and mechanistic insight that could inform the design of cleaner, more efficient syngas technologies.
Palladium-based catalysts are widely studied for methane-to-syngas conversion, a route that offers energy-efficient alternatives to steam reforming. Yet the fine details of how partial oxidation of methane (POM) proceeds on such surfaces have remained elusive.
To address this, the team used high-resolution operando transmission electron microscopy (TEM) to monitor palladium nanoparticles inside a functional microreactor under industrially relevant conditions. Simultaneously, mass spectrometry tracked product formation, while density functional theory (DFT) calculations mapped the energy landscape of methane activation and oxidation pathways.
The results show that catalytic activity arises from a synergy between palladium (Pd) and palladium oxide (PdO) phases. Metallic Pd facilitates methane dehydrogenation, generating surface carbon and hydrogen, while PdO oxidizes the carbon to carbon monoxide. The most efficient catalysis occurs at the interface between the two phases – demonstrating that neither Pd nor PdO alone is sufficient.
“The two phases take on different tasks,” explained Günther Rupprechter, co-author of the study, in a recent press release. “The palladium dehydrogenates methane to carbon and hydrogen, while the palladium oxide oxidizes the carbon to CO.”
The operando-TEM setup, which enables atomic-resolution imaging during ongoing reactions, marks a significant advance in catalyst characterization. The approach allows researchers to distinguish subtle structural changes – such as PdO formation, particle faceting, and interface migration – that occur under working conditions, rather than in static or idealized environments.
“Using computational modeling, we had previously looked into Pd nanoparticle oxidation and CO oxidation, so that the extension to methane oxidation was a very promising target,” said co-author Alexander Genest.
The team also noted that total oxidation to CO₂ and H₂O occurs when oxygen coverage is too high – an unwanted side reaction. This insight could help design more selective catalysts that suppress overoxidation while maximizing syngas yield.
“This new operando-TEM study extends this work to industrial conditions,” Rupprechter added. “Supported by the MECS Cluster of Excellence, we will soon have special reactor cells also available at TU Wien for similar operando-TEM examination.”
Newsletters
Receive the latest analytical science news, personalities, education, and career development – weekly to your inbox.
