THE REACTION OF METHANE WITH CARBON-DIOXI DE OVER THE CATALYSTS BASEDON LAFEO3

The reactions of methane and carbon dioxide over the catalysts based o n the perovskite structual oxide, LaFeO3, were examined. The reactions were carried out at 923 similar to 1073 K and the conversions of meth ane and carbon dioxode attained to 10 similar to 27% and 12 similar to 46%, respectively, producing CO, H-2 and H2O. It was found that two r eactions exhibited below occurred at the same time, CH4+3CO(2)-->4CO+2 H(2)O and CH4+CO2-->2CO+2H(2). The catalysts substituted with alkali m etal or alkali earth metal for a part of La or Fe in LaFeO3 catalyst f ormed C-2 compounds (C2H6, C2H4). The substitution effect of alkali me tals was superior to that of the catalysts substituted with alkali ear th metals. When 30% of Fe was replaced with alkali metals (M) such as LaFe(0.7)M(0.3)O(3-delta), the highest selectivity to C-2 compounds wa s obtained. The relationship between acid, base properties of the cata lysts and C-2 compounds selectivity was examined. Th acidic surface on the catalyst produced mainly CO and H-2 and basic one promoted to the C-2 compound selectivity. By the reaction of CH4 only and the TPD (Te mperature Programmed Desorption) measurements, it could be clarified t hat the oxygen on the LaFeO3 catalyst was mobile and that on the subst ituted with alkali metal rather hardly moved. These facts will be rela ted to the reaction activity to the C-2 compounds selectivity. By comp arison with the results of XPS the active species of oxy (O-, O-2(2-)) on the catalyst surface were supposed to enhance C-2 compounds select ivity.