Abstract: The selectivity of oxidative coupling of methane was greatly enhanced by adding Li toLa₂O₃.By using quenching and ESR technique, O₂^- species were found on Li/La₂O₃, butnot on the single La₂O₃.TPD measurements from 77K to room temperature were performedon methane preadsorbed on Li/La₂O₃ and single La₂O₃.Ethane desorbed during theTPD of Li/La₂O₃, but could not be detected in that of single La₂O₃.It is considered thatthe addition of Li to La₂O₃ gives rise to some basic sites, which are favorable to the coup-ling reaction, and this addition decreases the surface area, resulting in repression of thefurther oxidation of CH₃.radicals.

Key words: methane, oxidative coupling, lanthanum oxide, lithium, active oxygen