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From Active‐Site Models to Real Catalysts: Importance of the Material Gap in the Design of Pd Catalysts for Methane Oxidation
Author(s) -
Doan Hieu A.,
Sharma Munish K.,
Epling William S.,
Grabow Lars C.
Publication year - 2017
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201601333
Subject(s) - catalysis , methane , anaerobic oxidation of methane , density functional theory , robustness (evolution) , heterogeneous catalysis , chemistry , reactivity (psychology) , palladium , rational design , active site , computational chemistry , materials science , chemical physics , nanotechnology , organic chemistry , medicine , biochemistry , alternative medicine , pathology , gene
Rapid computational screening to aid novel catalyst design has evolved into an important and ubiquitous tool in modern heterogeneous catalysis. A possible shortcoming of this approach, however, is the material gap, that is, simplified computational models used for catalyst screening do not always capture the complexity of real catalytic systems. Here we investigate the importance of the material gap for complete methane oxidation over supported Pd/γ‐Al 2 O 3 catalysts using a combination of DFT simulations and temperature‐programmed oxidation experiments. The Pd/γ‐Al 2 O 3 active site was approximated by four models of increasing complexity, namely Pd(1 0 0), Pd(2 1 1), PdO(1 0 1), and Pd 10 /γ‐Al 2 O 3 (1 1 0), and each was also modified with metal promoters to discover reactivity trends. Although the unpromoted Pd model surfaces exhibit different methane activation activities, our DFT results indicate that an experimentally verified performance trend can be predicted for their promoted counterparts irrespective of the active‐site representation. We attribute the robustness of the trend predictions in this particular system to localized changes in the electron density during methane activation. Overall, our work supports the commonly practiced active‐site model simplifications during computational catalyst screening and provides fundamental insight into the qualitative agreement between theory and experiment for methane oxidation over promoted Pd catalysts.