Structural Evolution of Iron-Loaded Metal-Organic Framework Catalysts for Continuous Gas-Phase Oxidation of Methane to Methanol

Catalytic partial oxidation of methane presents a promisingrouteto convert the abundant but environmentally undesired methane gasto liquid methanol with applications as an energy carrier and a platformchemical. However, an outstanding challenge for this process remainsin developing a catalyst that can oxidize methane selectively to methanolwith good activity under continuous flow conditions in the gas phaseusing O-2 as an oxidant. Here, we report a Fe catalyst supportedby a metal-organic framework (MOF), Fe/UiO-66, for the selectiveand on-stream partial oxidation of methane to methanol. Kinetic studiesindicate the continuous production of methanol at a superior reactionrate of 5.9 x 10(-2) mu mol(MeOH) g(Fe) (-1) s(-1) at 180 degrees C and high selectivity toward methanol, with the catalytic turnoververified by transient methane isotopic measurements. Through an arrayof spectroscopic characterizations, electron-deficient Fe speciesrendered by the MOF support is identified as the probable active sitefor the reaction.