Investigating the role of pore aperture sizes in controlling the methane to methanol conversion over Fe-based metal-organic frameworks

Fe-based metal-organic frameworks (MOFs) are promising catalytic platforms to accomplish the efficient oxidation of methane to methanol (MTM). Current artificial catalysts such as MOFs and zeolites cannot however sustain multiple MTM reaction cycles because of active site (AS) deactivation, an issue recently suggested to be due to the escape of methyl radicals from the Fe ASs by diffusion through pore apertures larger than 4.2 Å. Herein we propose a combined XAS/XRD study to investigate the evolution of the structural/electronic properties of Fe sites during the N2O-mediated MTM conversion in a series of triiron node-based MOFs exhibiting pore apertures in the 3.0–8.6 Å range. The in situ experiment targeting the Fe(II) MOF centers able to form Fe(IV)=O sites active for the MTM conversion will desirably allow us to quantify the amount of Fe(II) sites regenerated after each performed reaction cycle, rationalizing the effect played by the size of pore apertures in MOF deactivation.