La1-xCaxCoO3 perovskite-type oxides. Preparation, characterisation, stability and catalytic potentiality for the total oxidation of propane

N. A. MERINO; B. P. BARBERO; P. GRANGE; L. E. CADÚS

JOURNAL OF CATALYSIS

Elsevier

Lugar: Shannon, Irlanda; Año: 2005 vol. 231 p. 232 - 244

0021-9517

La1-xCaxCoO3 (x = 0, 0.2, 0.4, 0.5) perovskite-type oxides were prepared by citrate method and characterised by different techniques. Thermogravimetry, XRD and specific surface area results were used to choose the best synthesis conditions. From the XRD results, the crystalline structure was refined using the Rietveld method. Substitution for La with Ca does not modify the preparation process of the perovskites but slightly changes the crystalline structure. An excess of lanthanum was detected by ICP, which would be at the surface as an oxide susceptible to be carbonated. The reactivity of the different oxygen species was studied from the results of temperature programmed desorption of oxygen (O2-TPD) and temperature programmed reduction (TPR). The catalytic potentiality was tested in propane total oxidation. The close paralellism between the catalytic activity and the oxygen species amount adsorbed on the surface oxygen vacancies indicates that the propane oxidation on La1-xCaxCoO3 catalysts proceeds through a suprafacial reaction mechanism.