Catalysts based on BaZrO3 with different elements incorporated in the structure I:: BaZr(1-x)PdxO3 systems for total oxidation

New catalytic systems, synthesized by a variant of citrate route, are proposed for total oxidation reactions. They consist of solid solutions-barium, zirconium, palladium and oxygen-with a perovskite structure and a formula BaZr(1-x)PdxO3. Detailed analysis of the X-ray diffraction (XRD) diffractograms and the TGA cycles show that Pd is randomly distributed as Pd-IV among the B sites of the perovskite, together with Zr. The full reduction of the catalyst is completed at around 1450 degreesC, whereas the re-oxidation of the reduced palladium occurs 150 degreesC-higher than for Pd-IV supported on gamma-alumina. The catalysts were tested for the catalytic combustion of methane; it was found that, although the catalysts tested were unsupported, the light-off temperature at 20% of methane conversion was roughly 400 degreesC. These preliminary results suggest that these systems might be suitable for both low and high temperature applications. (C) 2003 Elsevier B.V. All rights reserved.