CATALYTIC REFORMING OF METHANE WITH CARBON-DIOXIDE ON LABO3 (B = CO, NI, FE, CR) CATALYSTS

The reforming reactions of CH4 with CO2 diluted with He on perovskite structural oxides, LaBO3 (B = Co. Ni, Fe, Cr), were examined. The reac tion activity at 1073 K followed the order LaCoO3 > LaNiO3 > LaFeO3 > LaCrO3, and the highest selectivities to CO and H-2 were obtained on a LaCoO3 catalyst. The reaction on the LaCoO3 catalyst under the reacti on condition of CH4/CO2 = 1 showed a H-2/CO ratio of I; the ratio was less than 1 on other catalysts. In the initial stage of the reactions of CH4 + CO2 on LaCoO3 and LaNiO3 catalysts, an induction period accom panying the reduction of the catalysts was observed. During the reform ing reaction, both the LaCoO3 and LaNiO3 catalysts were decomposed by reduction to Co to Ni metal and La2O3. No induction period, however, w as observed in the reaction on the LaFeO3 and LaCrO3 catalysts, which were stable during the reaction. The high activity of the decomposed L aCoO3 catalyst is ascribed here - as a result of EPMA, SEM analysis an d of comparison with the reaction behaviors of Co catalysts supported on La2O3 - to the high concentration of metallic cobalt uniformly disp ersed as fine particles on the catalyst surface. The reaction mechanis m on the cobalt metal was inferred from the results of the reaction of CH4 or CO2 alone on the decomposed LaCoO3 catalyst.