Oxidation of methane to methanol on the surface of FeZSM-5 zeolite

In our previous work using FeZSM-5 zeolite with increased concentration of α-sites (100 μmol/g), the oxidation of methane by α-oxygen predeposited from nitrous oxide was studied at room temperature. The reaction proceeded by hydrogen abstraction mechanism yielding methoxy and hydroxy groups bound to α-sites.The present work conducted with the same zeolite is devoted to methane oxidation by N2O in the process of α-oxygen deposition at 160 °С. Under these conditions, the reaction was shown to proceed at a stoichiometric ratio СН4:N2O = 1:1 yielding directly methanol. Spillover of methanol from α-sites liberates them for further events of α-oxygen deposition, thus converting the reaction to a “quasicatalytic” mode that runs up to turnover number exceeding 3 with no product desorption into the gas phase. A part of methanol is converted to dimethyl ether, traces of acetaldehyde, and some amount of non-extractable products.Mechanism of the reaction is discussed.

Graphical abstractMethane oxidation by N2O was studied at 160 °C on the FeZSM-5 surface with increased concentration of α-sites (100 μmol/g). The reaction was shown to lead directly to methanol. Spillover of methanol from α-sites provides a “quasicatalytic” mode of the reaction with TON > 3.Figure optionsDownload full-size imageDownload high-quality image (45 K)Download as PowerPoint slideHighlights► Methane oxidation by N2O on FeZSM-5 α-sites at 160 °C leads directly to methanol. ► Methanol spillovers from α-sites providing “quasicatalytic” mode of reaction (TON > 3). ► A part of methanol is converted to DME and non-extractable products.