Abstract
The active site of CO dissociation on a cobalt nanoparticle, relevant to the Fischer-Tropsch reaction, can be computed directly using density functional theory. We investigate how the activation barrier for direct CO dissociation depends on CO coverage for step-edge and terrace cobalt sites. Whereas on terrace sites increasing coverage results in a substantial increase of the direct CO dissociation barrier, we find that this barrier is nearly independent of CO coverage for the step-edge sites on corrugated surfaces. A detailed electronic analysis shows that this difference is due to the flexibility of the adsorbed layer, minimizing Pauli repulsion during the carbon-oxygen bond dissociation reaction on the step-edge site. We constructed a simple first-principles microkinetic model that not only reproduces experimentally observed rates but also shows how migration of carbon species between step-edge and terrace sites contributes to methane formation.
Original language | English |
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Pages (from-to) | 7365-7372 |
Number of pages | 8 |
Journal | ACS Catalysis |
Volume | 9 |
Issue number | 8 |
DOIs | |
Publication status | Published - 2 Aug 2019 |
Keywords
- DFT
- Fischer-Tropsch synthesis
- activation energy
- lateral interactions
- microkinetic modeling