Surface properties and catalytic performance of La1−xSrxFeO3 perovskite-type oxides for methane combustion

La1−xSrxFeO3 (x = 0.0–1.0) perovskites were prepared and tested for the combustion of methane. X-ray diffraction (XRD) patterns revealed the presence of a single perovskite structure for substitutions 0 less-than-or-equals, slant x less-than-or-equals, slant 0.3, however Fe2O3, SrCO3 and SrFeO3 phases were observed for substitutions x > 0.3. The results of activity test indicate that with La1−xSrxFeO3 as the catalyst, the combustion of methane can take place at low temperatures around 400 °C. Partial substitution of La with Sr increases the activity and an optimal substitution fraction (x = 0.5) exists in the La1−xSrxFeO3 catalysts. Catalyst activity can be well correlated to the product of the specific surface area and atomic ratio of Fe to La + Sr on the catalyst surface. Experimental results of O2-TPD and CH4-TPD in the range of 350–500 °C indicate that the amount of oxygen desorbed from the La1−xSrxFeO3 catalysts is far larger than that of methane. Therefore, it can be proposed that the catalytic oxidation of CH4 over these catalysts proceeds with the surface reaction between CH4 in the gas phase and the adsorbed O2. Addition of water vapor or CO2 to the feed inhibited catalyst activity, but the inhibition was reversible and became negligible at high reaction temperature.