Regensburg 2022 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 11: Crystal Structure Defects / Real Structure / Microstructure

KFM 11.4: Talk

Tuesday, September 6, 2022, 10:30–10:50, H7

Ab Initio Thermodynamics for Surface Motifs of the M1 Selective Oxidation Catalyst — •K. Nam¹, Y. Lee¹, L. Masliuk², T. Lunkenbein², A. Trunschke², C. Scheurer¹, and K. Reuter¹ — ¹Theory Dept., Fritz-Haber-Institut der MPG, Berlin — ²Inorganic Chemistry Dept., Fritz-Haber-Institut der MPG, Berlin

The activity and selectivity of heterogeneous catalysts can be altered noticeably by small changes in different factors such as bulk composition, dopants, defects, reaction conditions, etc. The effects of these factors are furthermore interrelated in non-trivial ways. As an important first step to rationally disentangle them, we here aim to understand their influences on the local atomic-scale structural motifs offered by the catalyst. Specifically, we do this for the M1 structural modification of (Mo,V)O_x and (Mo,V,Te,Nb)O_x as an active catalyst for the oxidative dehydrogenation reaction of ethane to ethylene.

The large primitive cell of this M1 catalyst challenges a detailed study by means of predictive-quality first-principles calculations. To this end, we deconstruct the primitive cell into ‘rod-like structures’ of surface motifs with various oxygen content, faithfully modeling reported data from electron microscopy [1]. Ab initio thermodynamics then allows us to explore the effect of varying reaction conditions on the stability of these motifs and thus on M1 catalyst surfaces. Exploiting the data thus generated to train a machine-learn potential we can specifically rationalize the influence of vanadium and niobium doping on the active surface structure.

[1] L. Masliuk et al., J. Phys. Chem. C 121, 24093 (2017).