Scheme 1. Diagram of plasma-driven direct oxidation of methane to methanol on Cu-MOR catalysts, aiming to emphasize the active sites of zeolite-confined Cu2+ species.
This study presents an investigation into the performance of Cu-MOR catalysts prepared using both wetness impregnation and ion exchange methods in plasma-catalytic DOMtM. The results reveal that ion exchange mainly leads to the formation of zeolite-confined Cu2+ species in Cu-MOR, exhibiting excellent catalytic performance (7.9% CH4 conversion and 51% CH3OH selectivity), as shown in Scheme 1. In contrast, wetness impregnation predominantly results in the formation of CuO particles in Cu-MOR, hindering the DOMtM reaction while inducing over-oxidation into CO and CO2. The correlation of the catalytic performance with catalyst characterization results unequivocally demonstrates that zeolite-confined Cu2+species serve as the active sites for DOMtM, providing valuable information to the advancement of plasma-catalytic systems in the context of DOMtM.
Experimental section