Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 81: Heterogeneous Catalysis III
O 81.4: Talk
Thursday, March 20, 2025, 11:15–11:30, H6
Selectivity trends in CO hydrogenation over transition metal surfaces — •David Degerman1,2, Patrick Lömker1, Markus Soldemo1, Fernando Garcia-Martìnez3, Robin Yoël Engel1,2, Martin Beye1,2,3, and Anders Nilsson1,2 — 1Department of Physics, Stockholm University, 114, 21, Stockholm, Sweden — 2WISE - Wallenberg Initiative Materials Science for Sustainability, Department of Physics, Stockholm University, 114, 21, Stockholm, Sweden — 3Deutsches Elektronen Synchrotron, DESY, Photon Science, Notkestraße, 22607, Hamburg, Germany
Understanding the selectivity of heterogeneously catalyzed CO hydrogenation is increasingly important for the transition towards a sustainable chemical industry. While theoretical studies yielded a model based on the competition of various elementary surface reactions, we need experimental observation of the surface's chemical state to verify the mechanistic origin of the selectivity. Here, we compare in-situ x-ray photoelectron spectra over operating single crystal catalysts (200 to 325 °C, 150 mbar) of Fe, Rh, Ni, Co and Cu and infer from the observed trends which mechanistic steps decides the product distribution for each material. In particular, we find that the chemisorption energies of C and O (commonly used descriptors for activity and selectivity) qualitatively predicts the rate-limiting step of catalysts, but fails when the reaction mechanism of Ni and Fe is fundamentally altered due to reaction-induced carburization. This work emphasizes that the complete chemical overview provided by photoemission spectroscopy is required to understand the selectivity of CO hydrogenation.
Keywords: Selectivity; Reaction mechanism; CO hydrogenation; X-ray Photoelectron Spectroscopy; Heterogenous catalysis