Synthesis of perovskite-type (La1–xCax)CoO3 at low temperature using ethylene glycol and citric acid

To synthesize perovskite-type (La1–xCax) CoO3 with good crystallinity (regularity of ions), a gel was prepared by adding ethylene glycol and citric acid to an aqueous solution of La(NO3)3 Æ 6H2O, CaCO3, and Co(CH3COO)2 Æ 4H2O. Perovskite-type (La1–x Cax)CoO3 (0.0 £ x £ 0.3) was obtained by firing the gel above 600 C in air for 3 h. Samples were examined for oxygen content, crystallite size, specific surface area, and the catalytic activity of CH4 oxidation. The samples were also investigated by transmission electron microscopy (TEM). Based on the variation in crystallite size and in the average particle size, the (La1–xCax)CoO3 particle became finer as x increased. In all samples, CH4 oxidation occurred above 300 C. The catalytic activity of (La1–xCax)CoO3 fired at 700 C monotonously increased as x increased.