Abstract: The structures and the catalytic properties of mixed oxides, LiLa_1-xMn_xO₂, have been studied by means of XRD, IR, XPS and SEM. The effects of reaction conditions were examined. The results showed that a series complex oxides could be formed at different X values. The ternary complex oxides La₂Mn_1-yLi_yO₄ were found to be the active phase for the oxidative coupling of methane, in which the defect cluster Li⁺-O^--Mn²⁺ was formed as a result of the substitution of part Li⁺ for Mn²⁺ in La₂MnO₄. That increased the concentration of active oxygen species O^- and enhanced its regeneration rate. It was the premiere factor of the complex oxide to possess a higher catalytic activity. The pulse reaction results showed that all the reations:CH₄→CH₃ ·2CH₃·→C₂H₆, and C₂H₆→C₂H₄ could take place on the catalyst surface, while the CO₂ was only formed in the gas phase. A higher C₂ yield of 23.9% was obtained at 780℃.

Key words: methane, La-Mn-Li complex oxide, catatytic, oxidative coupling