METHANE OXIDATIVE COUPLING OVER A NEW TYPE OF CATALYSTS CONTAINING FLUORIDES

A series of alkaline earth oxides, transition metal oxides catalysts promoted with fluorides have been developed, and improved low-temperature(500-600{degrees}C) catalytic properties for the methane oxidative coupling reaction have been observed, for example, over LaF{sub 3}-La{sub 2}O{sub 3} catalysts in comparison with undoped LaF{sub 3} or La{sub 2}O{sub 3}. Thus, the 80 mol% LaF{sub 3}-La{sub 2}O{sub 3} catalyst gives a C{sub 2} yield of 14.7% and C{sub 2} selectivity of 48.2% at 550{degrees}C. The structures of the catalysts have been detected by XRD. The oxygen adspecies on the surface of La{sub 2}O{sub 3}, LaF{sub 3} and 80 mol% LaF{sub 3}-La{sub 2}O{sub 3} catalysts were determined by LRS, XPS and TPD, showing remarkably the existence of O{sub 2}{sup {minus}}, O{sub 2}{sup n{minus}} (1