Framework effects on activation and functionalisation of methane in zinc‐exchanged zeolites.

Abstract

The first selective oxidation of methane to methanol is reported herein for zinc‐exchanged MOR (Zn/MOR). Under identical conditions, Zn/FER and Zn/ZSM‐5 both form zinc formate and methanol. Selective methane activation to form [Zn‐CH 3 ] + species was confirmed by 13 C MAS NMR spectroscopy for all three frameworks. The percentage of active zinc sites, measured through quantitative NMR spectroscopy studies, varied with the zeolite framework and was found to be ZSM‐5 (5.7%), MOR (1.2%) and FER (0.8%). For Zn/MOR, two signals were observed in the 13 C MAS NMR spectrum, resulting from two distinct [Zn‐CH 3 ] + species present in the 12 MR and 8 MR side pockets, as supported by additional NMR experiments. The observed products of oxidation of the [Zn‐CH 3 ] + species is shown to depend on the zeolite framework type and the oxidative conditions used. These results lay the foundation for developing structure‐function correlations for methane conversion over zinc‐exchanged zeolites