4 Conclusion
We investigated the catalytic performance of Cu-MOR catalysts, prepared by ion-exchange and wetness impregnation, for plasma-catalytic DOMtM in CH4/O2 plasma. The Cu-MOR IE-3 catalyst, synthesized through ion-exchange, demonstrates the most favorable catalytic outcomes, with 7.9% CH4 conversion and 51% CH3OH selectivity. Conversely, the Cu-MOR catalysts prepared by wetness impregnation exhibit tendencies towards over-oxidation of CH4 to CO and CO2, particularly for the catalysts with higher loadings. The combination of our catalyst characterizations reveals that ion exchange predominantly leads to the formation of zeolite-confined Cu2+ species within Cu-MOR, whereas wetness impregnation primarily yields CuO particles. Specifically, zeolite-confined Cu2+ species function as the active sites for plasma-catalytic DOMtM, while the presence of CuO clusters and particles proves detrimental to DOMtM. instead facilitating over-oxidation reactions leading to CO and CO2production. Finally, the surface species on the catalyst, detected byin-situ FTIR, further corroborate the pivotal role of zeolite-confined Cu2+ species in plasma-catalytic DOMtM.