Structural and morphological properties of Co–La catalysts supported on alumina/lanthana for hydrocarbon oxidation

Two Al2O3(24 wt%)–La2O3(76 wt%) supported Co–La oxides with Co loading 4 wt% and different La content (1 and 9 wt%) were prepared by co-impregnation of the support, the aluminum–lanthanum oxide, with cobalt and lanthanum nitrates in aqueous solution and successive calcination at 800 °C for 4 h. The alumina–lanthana was synthesized by the sol–gel method. mples were characterized by X-ray diffraction (XRD) and Rietveld refinement in order to identify the crystalline phases and their relative weight. H2-TPR (Temperature Programmed Reduction) experiments were recorded with the aim to identify the different Co phases present. Co3O4 and LaCoO3 were formed for La loading of 1%, whereas at higher La loading (9%) LaCoO3 and La2O3 oxide prevailed. In both catalysts LaAlO3 phase was also detected. erved by BET and SEM characterizations, the morphology of the two catalysts was somewhat affected by La:Co atomic ratio and differed dramatically from those of the reference bulk oxides, Co3O4 and the mixed phase LaCoO3/La2O3. Activity tests in C3H6 and CH4 combustion were carried out in order to discriminate the catalytic properties of different phases formed (Co3O4, LaCoO3, La2O3, LaAlO3).