Mechanistic Aspects of CO Activation and C–C Bond Formation on the Fe/C- and Fe-Terminated Fe3C(010) Surfaces

Abstract

To understand the reaction mechanisms of iron-based Fischer–Tropsch synthesis in converting synthesis gas into chemicals and hydrocarbons, we computed CO activation and C–C bond formation on the Fe3C(010) phase as an active catalyst systematically and comparatively on the basis of spin-polarized density functional theory. On the Fe/C-terminated Fe3C(010) surface, C–O dissociation of CO and CHxO (x = 1, 2, and 3) with higher barriers is not accessible, while consecutive hydrogenation of adsorbed CO to methanol and surface carbon atom to methane is accessible with low overall barriers and exothermic reaction energies. However, the formed CH3 from surface carbon hydrogenation can couple with adsorbed CO to form surface acetyl (CH3CO), resulting in the formation of the initial C–C bond with comparably low overall barrier and exothermic reaction energy. The formed acetyl can be deoxygenated to surface CH3C, which can couple with surface carbon to form CH3CC. The formation of CH3CO and CH3CC reveals that chain ...