Methane‐to‐Methanol on Mononuclear Copper(II) Sites Supported on Al₂O₃: Structure of Active Sites from Electron Paramagnetic Resonance.

Meyet, Jordan; Ashuiev, Anton; Noh, Gina; Newton, Mark A.; Klose, Daniel; Searles, Keith; Bavel, Alexander P.; Horton, Andrew D.; Jeschke, Gunnar; Bokhoven, Jeroen A.; Copéret, Christophe

The selective conversion of methane to methanol remains one of the holy grails of chemistry, where Cu‐exchanged zeolites have been shown promote this reaction under stepwise conditions. Over the years, several active sites have been proposed, ranging from mono‐, di‐ to trimeric CuII. Herein, we report the formation of well‐dispersed monomeric CuII species supported on alumina using surface organometallic chemistry and their reactivity towards the selective and stepwise conversion of methane to methanol. Extensive studies using various transition alumina supports combined with spectroscopic characterization, in particular electron paramagnetic resonance (EPR), show that the active sites are associated with specific facets, which are typically found in γ‐ and η‐alumina phase, and that their EPR signature can be attributed to species having a tri‐coordinated [(Al2O)CuIIO(OH)]− T‐shape geometry. Overall, the selective conversion of methane to methanol, a two‐electron process, involves two monomeric CuII sites that play in concert.

ELECTRON paramagnetic resonance; ELECTRON paramagnetic resonance spectroscopy; ORGANOMETALLIC chemistry; COPPER; REACTIVITY (Chemistry); SURFACE chemistry; STEAM reforming

Angewandte Chemie, 2021, Vol 133, Issue 29, p16336

0044-8249

Academic Journal

10.1002/ange.202105307