The role of Mo species in Ni–Mo catalysts for dry reforming of methane

Abstract

The Ni–Mo catalyst has attracted significant attention due to its excellent coke-resistance in dry reforming of methane (DRM) reaction, but its detailed mechanism is still vague. Herein, Mo-doped Ni (Ni–Mo_x) and MoO_x adsorbed Ni surfaces (MoO_x@Ni) are employed to explore the DRM reaction mechanism and the effect of coke-resistance. Due to the electron donor effect of Mo, the antibonding states below the Fermi level between Ni and C increase and the adsorption of C decrease, thereby inhibiting the carbonization of Ni. On account of the strong Mo and O interaction, more O atoms gather around Mo, which inhibits the oxidation of Ni and may promote the formation of MoO_x species on the Ni–Mo catalyst. The presence of Mo–O species promotes the carbon oxidation, forming a unique redox cycle (MoO_x ↔ MoO_x−1) similar to the Mars–van Krevelen (MvK) mechanism, explaining the excellent anti-carbon deposition effect on the Ni–Mo catalyst.