Ethanol combustion over strontium- and cerium-doped LaCoO3 catalysts

Ce- or Sr-doped LaCoO3 bulk perovskites were prepared by citric acid method as well as 10 wt.% of LaCoO3 was deposited on alumina carrier stabilized with lanthanum. Properties of prepared materials were characterized by determination of surface area, acid-basic properties and XRD, XPS, TPDO2, H-2-TPR measurements as well as catalytic activity and selectivity for ethanol combustion was tested. It was found that substitution of La in LaCoO3 with either Sr or Ce has only small effect on its activity in ethanol combustion. Strontium inserted into LaCoO3 structure increases basic character of the perovskite surface as well as selectivity to acetaldehyde (ACA). Substitution of La with cerium has no effect on the concentration of basic sites and does not affect the selectivity to ACA. Activity of LaCoO3-based catalysts in ethanol combustion and their selectivity to ACA formation can be explained on the basis of the presence of both a-oxygen species and sites with basic character on the material surface. Acid-basic properties of supported LaCoO3 are dominated by acidic character of the carrier. Results of XPS and H-2-TPR measurements of LaCoO3 supported on La-Al2O3 suggest that perovskite remains in strong interaction with carrier and probably is partially decomposed. Deposition of perovskite on stabilized carrier significantly increases the rate of ethanol combustion. (c) 2006 Elsevier B.V. All rights reserved.