Active Ag species in MFI zeolite for direct methane conversion in the light and dark

Photo-induced methane conversion was examined over Ag-MFI zeolite at room temperature. On the oxidized Ag-MFI zeolite, containing Ag⁺ exchanged cations, huge amounts of methane were adsorbed, even in the dark, and then converted to mainly ethane upon photo-irradiation without H₂ production. It was revealed that Ag _n ⁺ small clusters were formed at the expense of Ag⁺ ion during this photoreaction, and probably hydrogen would be stored as H⁺ on the ion-exchange sites instead of Ag⁺. On the other hand, the reduced sample containing larger clusters converted methane into alkene even without photo-irradiation.