The effect of preparation: Pechini and Schiff base methods, on adsorbed oxygen of LaCoO3 perovskite oxidation catalysts

LaCoO3 prepared by the sol–gel method using a novel Schiff base complex has a superior property of high ratio of adsorbed oxygen to lattice oxygen to that prepared by the citrate complex-Pechini method. The as-prepared gels, characterized by Fourier transform infrared spectroscopy (FTIR), showed that both lanthanum and cobalt formed complexes before calcination. The IR spectra revealed that CO32− and NO3−, generated on the sample surfaces during heat treatment, could form gaseous compounds and leave vacant sites for oxygen to adsorb. Ratios of adsorbed oxygen (α) to lattice oxygen (β), quantified by X-ray photoemission spectroscopy showed that LaCoO3 prepared by the Schiff base complex method produced higher ratios than that prepared by the citrate complex-Pechini method. A DRIFTS study of toluene oxidation on LaCoO3 showed that small size perovskites without impurity and with a high ratio of adsorbed oxygen (α) to lattice oxygen (β) performed well. LaCoO3 prepared by the Schiff base complex showed higher catalytic activity than that prepared by the citrate complex-Pechini method due to the higher ratio of adsorbed oxygen (α) to lattice oxygen (β).