CO hydrogenation conversion driven by micro-environments of active sites over iron carbide catalysts

Abstract

Essentially clearing the structure–activity relationship between iron carbide catalysts involving multiple active centers to understand the reaction mechanism of CO hydrogenation conversion process is still a great challenge. Here, two main micro-environment factors, namely electronic properties and geometrical effects were found to have an integrated effect on the mechanism of CO hydrogenation conversion, involving active sites on multiple crystal phases. The Bader charge of the surface Fe atoms on the active sites had a guiding effect on the CO activation pathway, while the spatial configuration of the active sites greatly affected the energy barriers of CO activation. Although the defective surfaces were more conducive to CO activation, the defective sites were not the only sites to dissociate CO, as CO always tended to dissociate in a wider area. This synergistic effect of the micro-environment also occurred during the CO conversion process. Surface C atoms on relatively flat configurations were more likely to form methane, while the electronic properties of the active sites could effectively describe the C-C coupling process, as well as distinguish the coupling mechanisms.