Conversion of Methane to Methanol on Copper Mordenite: Redox Mechanism of Isothermal and High-Temperature-Activation Procedures

In the search for a commercially viable process to convert methane directly to methanol, the low-temperature isothermal process represents a promising new reaction pathway, because of its easier operation at lower temperatures than previously proposed processes with a high activation temperature. Isothermal methane to methanol conversion on copper-exchanged mordenite was examined by in situ XAS and compared to the conventional high-temperature activation procedure. Despite the copper remaining partially hydrated during the isothermal procedure, methanol can form when elevated pressures are applied. By observing the reduction of copper during reaction at elevated pressures, the mechanism was found to be a two-electron reduction–oxidation reaction for the isothermal procedure, as in the high-temperature activation case.