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First-Principles Microkinetic Modeling of Methane Oxidation over Pd(100) and Pd(111)
dataset
posted on 2016-08-31, 00:00 authored by Mikkel Jørgensen, Henrik GrönbeckThe intrinsic activity
of Pd(100) and Pd(111) for methane oxidation
is investigated by Density Functional Theory (DFT)-based mean-field
microkinetic modeling. The model includes 32 reaction steps, and the
calculated turnover frequencies together with reaction orders compare
favorably with experimental data. On both surfaces, the reaction proceeds
via complete dehydrogenation of methane to elemental carbon followed
by different mechanisms for carbon oxidization. Pd(100) is found to
be more active than Pd(111) at temperatures from 400 to 1000 K. For
both surfaces, the reaction order in methane approaches unity with
increasing temperature. The reaction order in water is positive at
low temperatures owing to water-promoted carbon oxidation. Methane
dissociation is the main rate-controlling step for Pd(111), whereas
formation of COH and CO is also controlling the rate over Pd(100).
The present work uncovers the detailed reaction mechanisms for complete
methane oxidation over palladium, which can be used in catalyst design
to target the rate-controlling steps.