Kinetic study and effect of water on methane oxidation to methanol over copper-exchanged mordenite†
The selective oxidation of methane directly to methanol is currently one of the most studied topics. A promising approach, which received increasing attention during the past decade, is methane oxidation over copper-exchanged zeolites via chemical looping. In the present study, the kinetics of methane reacting over oxygen-activated copper-exchanged mordenite was studied by means of in situ infrared spectroscopy. Methoxy species and carbon monoxide are the primary reaction products and formed directly from methane. Partial poisoning with water after the oxygen activation and before the methane reaction leads to the decrease of methanol yield, which is associated with the blockage of at least two copper atoms in the active site per one water molecule. However, the poisoning is reversible and the increase of the methane pressure increases the activity of CuMOR due to the competitive adsorption over the active sites. As such, even if the zeolite is not fully dehydrated, low temperature isothermal conversion of methane to methanol via chemical looping becomes possible.