| Abstract
| - Density functional theory calculations have been carried out on the CO/H2 coadsorption on the (001), (110),and (100) surfaces of Fe5C2 for the understanding of the Fischer−Tropsch synthesis (FTS) mechanism. Thestable surface species changes with the variation of the H2 and CO coverage. Along with dissociated hydrogenand adsorbed CO in 2-, 3-, and 4-fold configurations, methylidyne (CsH) (Cs, surface carbon), ketenylidene(CsCO), ketenyl (CsHCO), ketene (CsH2CO), and carbon suboxide (CsC2O2) are computed as thermodynamicallystable surface species on Fe5C2(001) and Fe5C2(110) containing both surface iron and carbon atoms. Thesesurface carbon species can be considered as the preliminary stages for FTS. On Fe5C2(100) with only ironatoms on the surface layer, the stable surface species is dissociated hydrogen and CO with top and 2-foldconfigurations. The bonding nature of these adsorbed carbon species has been analyzed.
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