In order to synthesize perovskite-type LaCoO 3 with good surface crystallinity, the gel prepared by adding both ethylene glycol (EG) and citric acid (CA) to the aqueous solution of La(NO 3 ) 3 ·6H 2 O and Co(NO 3 ) 2 ·6H 2 O was fired at 600°C in air for 3 hours. The transmission electron microscopy (TEM) observation indicated that the particles of LaCoO 3 tended to have a uniform shape at EG/CA = 4. Although the specific surface area of LaCoO 3 synthesized using both EG and CA was slightly smaller than that of LaCoO 3 synthesized using only CA, the catalytic activity of CO oxidation became higher by adding EG.

X-ray photoelectron spectroscopy was performed to elucidate the catalytic activity of CH 4 oxidation on perovskite-type Ca(Mn 1Àx Ti x )O 3Àd synthesized at 1173 K in a flow of oxygen from a gel with citric acid and ethylene glycol. The Mn ion content decreases and the ratio of the Mn 31 ion in the Mn ion increases with increases in x. Ca(Mn 1Àx Ti x )O 3Àd has a high catalytic activity of CH 4 oxidation at x 5 0.4. These results indicate that the catalytic activity strongly depends on the Mn 31 ion content of the surface.