Catalytic activity for methane combustion of the perovskite-type La_1-xSr_xCoO_3-δ oxide prepared by the urea decomposition method

Four methods were adopted to prepare perovskite-type oxide with molar ratio of La/Sr/Co = 0.9/0.1/1.0. The oxide prepared by the urea decomposition method showed the highest catalytic activity for methane combustion and a good durability at 600 °C for 90. h. Surface structure features of this oxide were discussed by use of XPS data. This method was further applied to prepare other perovskite oxides with nominal degree of substitution x= 0.0, 0.2 and 0.3. Relation of catalytic activity with degree of substitution was discussed in view of cooperation of surface lattice oxygen vacancy with surrounding cobalt ions at lower oxidation states.