Theoretical investigation onto the reaction mechanism of dry reforming of methane on core–shell Cu-Ni-Pt ternary alloy clusters

Abstract

Dry reforming of methane (DRM) can not only solve the problem of greenhouse gas emissions, but also be used as a precursor step for the production of clean energy. In this paper, based on Cu55 cluster, core–shell Cu-Ni-Pt ternary alloy clusters were constructed by density functional theory (DFT). Based on theoretical calculation, the adsorption of intermediate species and reaction mechanism of DRM on clusters were discussed in detail. Compared with Cu55 cluster, Cu-Ni-Pt ternary alloy clusters show much lower energy barrier in CHX activation, which indicates that the latter is much more suitable for DRM reaction than the former. The different species would be adsorbed on Top1, Top2, Hol1 and Bri2 site of the cluster. Hol2 was not the active adsorption site of DRM species. For Cu-Ni-Pt ternary alloy clusters, CH4 decomposes into CH3*, and then CO2 is directly activated into CO* and O*. CH3* collides with O* species to produce CH3O*, and CH3O* further decays H* to produce CH2O*. Two molecules H* in the system interact to form H2*. CH2O* continuously dissociates two H* and transforms into CO*. Finally, two H* are combined to form H2*. The rate-determining step of this reaction pathway is CO2* activation.