Over 90% C₂₊ Selectivity in Kalium-Doped Manganese Perovskite Oxygen Carriers for Chemical Looping Oxidative Coupling of Methane with Plasma Assistance

Plasma-assistedchemical looping oxidative coupling of methaneis a potential route for the conversion of methane into value-addedC(2+) hydrocarbons under mild conditions. However, the lowC(2+) selectivity of traditional oxygen carriers limits furtherdevelopment. In this study, we report a series of kalium-doped LaMnO3 oxygen carriers. The optimal doping level of kalium is foundto be 1.0%, resulting in a C2+ selectivity of 92.67% at400 & DEG;C, and the performance remained stable after 20 redox cycles.Mechanistic studies show that 1.0% kalium doping inhibits the migrationof lattice oxygen (O-2 (2-)) from bulk tothe surface and the subsequent evolution of surface oxygen from electrophilicspecies (O-) to nucleophilic species (O2-). Therefore, the nucleophilic oxygen species (O2-) responsible for the overoxidation of the products was limited andin turn achieved a higher C2+ selectivity.