(626b) Gas-Phase Catalytic Oxidation of Methane into Methanol over Copper-Exchanged Zeolites with Molecular Oxygen

Roman, Y., MIT
Dinh, K., Massachusetts Institute of Technology
The direct catalytic conversion of methane to liquid oxygenated compounds, such as methanol or dimethyl ether, using molecular oxygen at low temperature is a grand challenge in C-H activation that has never been met. We report the first demonstration of direct, catalytic oxidation of methane into methanol with molecular oxygen over copper-exchanged zeolites at low reaction temperatures. Reaction kinetics studies show sustained catalytic activity and high selectivity over copper-exchanged ZSM-5 under mild conditions. Transient and steady state measurements with isotopically labeled molecules confirm catalytic turnover. Catalytic activity is observed for a variety of commercially available zeolite topologies. The catalytic rates and apparent activation energies are significantly affected by the zeolite topology, with caged-based zeolites (e.g., Cu-SSZ-13) showing the highest rates. Reactivity and characterization data demonstrate that the mono-(μ-oxo) dicupric site in copper exchanged ZSM-5 active for stoichiometric methane oxidation is not the catalytic site.