Single-Step Selective Oxidation of Methane by Iron-Oxo Species in the Metal-Organic Framework MFU-4l

The direct and selective conversion of methane to methanolcanbe considered a holy grail for catalysis research. In this work, westudy a metal-organic framework known as MFU-4l, modified bydesign to include highly reactive iron-oxo species for the catalyticC-H bond activation of methane. We investigate the oxidationof methane and the further potential oxidation of the product methanolusing N2O as an oxygen source and map the potential energylandscape of these reactions using density functional theory calculations.We show that the highest energy barrier encountered during the methaneoxidation process is not the C-H bond breaking but the activationof the iron center by N2O. Furthermore, the potential energylandscape for the C-H bond activation exhibits a large, high-energyplateau region instead of a sharp transition state, thus differingfrom the traditional radical rebound mechanism. This insight offersinteresting potential routes to enhance the catalytic activity ofthe catalyst, to hinder unwanted deactivation pathways, and to reducethe activity toward the over-oxidation of the product.