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.