OXIDATIVE COUPLING OF METHANE OVER THE OXIDES OF GROUP IIIA, IVA, AND VA METALS

Article abstract of DOI:10.1021/j100411a015

The conversion of methane to C2 hydrocarbons by oxidative coupling was studied on the oxides of group IIIA (3), IVA (4), and VA (5) metals over a temperature range of 550-700 deg C.The effect of the preparative method of the catalyst, of alkali promoters, and of supports was investigated in more detail with bismuth oxide.The addition of alkali, up to a concentration of 8 X 10²⁰ ions/g, promoted alumina-supported Bi2O3 catalysts, and a maximum was observed for the total carbon conversion and the C2 selectivity at Bi2O3 concentration of 3-10 wt percent in the Bi2O3-K2CO3-Al2O3 catalysts.It was also found that the yield of C2 hydrocarbons on the Bi2O3 catalysts strongly depended on the support: alumina was most efficient, followed by magnesia, while Bi2O3 supported on silica and titanium oxide was inactive under the present conditions.When supported on alumina and promoted by potassium, Bi2O3 was most active and selective followed by SnO2 and PbO in that order but Ga2O3, In2O3, Tl2O3, GeO2,, and Sb2O4 gave practically no C2 hydrocarbons at 640 deg C.The results of the present study and of the hydrogen-exhange reaction between CH4 and CD4 suggest that the Bi2O3-K2CO3-Al2O3 catalysts catalyze the oxidative coupling reaction as bifunctional catalysts.