Hydrogen abstraction from methane on cristobalite supported W and Mn oxo complexes: A DFT study

The oxidative coupling of methane using the MnNaW/SiO2 catalyst was considered for the W-Mn two-metal-site model on the (111) surface of alpha-cristobalite by DFT means in the cluster approximation. The crucial step of this process, namely, the hydrogen abstraction from methane is assumed to proceed on whether the terminal W=0 or the Mn=O group. The energy barrier for the methane dissociation on the tungsten species was predicted to be much higher than that for manganese. This allows one to suggest that the Mn species are responsible for hydrogen abstraction from methane. The W species are suggested to play a role in the ethane formation on the surface from tungsten bound methoxy group and govern selective oxidative dehydrogenation of ethane. (C) 2017 Elsevier B.V. All rights reserved.