About copper promotion in CH4 formation from CO hydrogenation on Fe(100): A density functional theory study

Abstract

The effect of Cu promoter on CH4 formation from CO hydrogenation on Fe(100) has been investigated using spin-polarized density functional theory computations on periodic slab models. Two pathways of CH4 formation are considered: (a) direct dissociation of CO followed by successive C hydrogenation and (b) successive hydrogenation of CO followed by deoxygenation of CHxO (x=1–3). On the clean and Cu doped surfaces, direct dissociation of CO followed by successive C hydrogenation is more favorable kinetically and the overall CH4 formation is endothermic. Compared with the clean surface, the Cu doped surface can suppress CH4 formation by raising the barrier from the co-adsorbed CO+4H. Methanol formation is unfavorable on both surfaces kinetically and thermodynamically. Reversely, methanol decomposition is favorable. It is also noted that Cu doping lowers the adsorption ability of the Fe(100) surface and therefore the adsorption energies of all species on the potential energy surfaces.