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O: Fachverband Oberflächenphysik
O 24: Catalysis: Structural Effects
O 24.7: Talk
Tuesday, March 17, 2015, 12:00–12:15, MA 144
Comparison of mean-field and kinetic Monte Carlo microkinetic models of CO methanation on Rh(211): Influence of lateral interactions between adsorbates — •Mie Andersen1, Andrew J. Medford2,3, Thomas Bligaard2,3, Jens K. Nørskov2,3, and Karsten Reuter1,2,3 — 1Theoretical Chemistry, Technische Universität München, Germany — 2SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, CA, USA — 3Department of Chemical Engineering, Stanford University, CA, USA
In heterogeneous catalysis microkinetic modeling is often carried out in the mean-field approximation (MFA), which assumes a rapid mixing of the adsorbates and leads to a uniform distribution of all atomic and molecular species on the surface. Here, we loosen some of the underlying assumptions inherent in the MFA by moving to a full kinetic Monte Carlo (KMC) description of relevant surface processes such as adsorption, diffusion, reaction, and desorption. Using CO methanation on Rh(211) as a test case and energetic input from density functional theory calculations, we compare the predicted coverages and turn-over-frequencies between mean-field and KMC microkinetic models. Further, we discuss simple first-order models for lateral interactions between adsorbates [1], where the statistically correct description of fluctuations and correlations in the coverage and binding sites of adsorbates in KMC is expected to outperform the MFA.
[1] Journal of Catalysis 307, 275-282 (2013)