Single-site trinuclear copper oxygen clusters in mordenite for selective conversion of methane to methanol

Abstract

Copper-exchanged zeolites with mordenite structure mimic the nuclearity and reactivity of active sites in particulate methane monooxygenase, which are enzymes able to selectively oxidize methane to methanol. Here we show that the mordenite micropores provide a perfect confined environment for the highly selective stabilization of trinuclear copper-oxo clusters that exhibit a high reactivity towards activation of carbon–hydrogen bonds in methane and its subsequent transformation to methanol. The similarity with the enzymatic systems is also implied from the similarity of the reversible rearrangements of the trinuclear clusters occurring during the selective transformations of methane along the reaction path towards methanol, in both the enzyme system and copper-exchanged mordenite.

Water-assisted oxygen activation during selective oxidation reactions

“…Owing to its superior activity and selectivity, Cu/ZSM-5 with MFI structure has attracted great interest; its active site was identified as a mono(m-oxo) dicopper core, [Cu-O-Cu] 2+ [68]. Compared to the 10-membered ring channels in MFI, the MOR structure has larger 12-membered ring pores that stabilize a trinuclear copper-oxo cluster [69]. The active site containing extra-framework radical oxygen is generated from the Cu-exchanged zeolite by an appropriate oxygen treatment followed by exposure to methane to form methanol.…”

A zeolitic vanadotungstate family with structural diversity and ultrahigh porosity for catalysis

“…With the combination of the unique properties of transition metals with ordered microporosity, major breakthroughs in applications have been achieved 6–8 . The classical methods to achieve this kind of combination is the direct modification of zeolites through ion-exchange 9 , modifying the framework disorderly 10 , and forming mixed tetrahedral and octahedral frameworks 11,12 . However, these approaches are not effective for introducing transition metals with a high content, precise locations, and well-ordered structure.…”

Direct Methylation of Benzene with Methane Catalyzed by Co/MFI Zeolite

“…(2)), was found to proceed on H‐ and Na‐MFI and its ion exchanged formed with Co, Mn and Cu salts;32,33 the valence of transition elements has not been mentioned in the papers. Also for the partial oxidation of methane into methanol, zeolite‐supported transition metal species were reported to show the catalytic activity 34, 35, 36, 37, 38. It has been known that zeolite (mainly MFI)‐supported metal species are active also for combustion of methane,39 reduction of NO x with methane,40 aromatization of methane14 and the activation of methane at low temperature 41.…”