3.1 Catalytic performance
Figures 1a and b illustrate the comparative catalytic performance of Cu-MOR catalysts prepared via ion exchange and wetness impregnation methods in DOMtM. In Figure 1a, the CH4 conversion and CH3OH selectivity of Cu-MOR catalysts demonstrate a volcano trend with increasing ion exchange cycles. Cu-MOR IE-3 exhibits the optimal catalytic performance, achieving 7.9% CH4conversion, 51% CH3OH selectivity, and 72% total selectivity for liquid oxygenates. As shown in Figure 1b, the Cu-MOR catalysts prepared through wetness impregnation reveal a gradual increase in CH4 conversion but a gradual decrease in CH3OH selectivity with increasing Cu loading, ranging from 2 wt.% to 20 wt.%. The 2 wt.% Cu-MOR catalyst displays 6.4% CH4 conversion with 48% CH3OH selectivity, slightly lower than the results of the Cu-MOR IE-3 catalyst. Conversely, the 20 wt.% Cu-MOR catalyst exhibits 77% CO2 selectivity, 17% total liquid oxygenates selectivity, and only 12% CH3OH selectivity. These experimental results suggest that the Cu-MOR IE-3 catalyst demonstrates superior performance in plasma-catalytic DOMtM.