Catalysts based on BaZrO_3 with different elements incorporated in the structure I:BaZr_(1-x)Pd_xO_3 systems for total oxidation

摘要

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)Pd_xO_3.Detailed analysis of the X-ray diffracton (XRD) diffractorams 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 deg C,whereas the re-oxidation of the reduced palladium occurs 150 deg C-higher than for Pd~IV supported on gamma-aumina.The catalysts were tested for the catalystic combustion of methane;it was found that,although the catalysts tested were unsupported,the light-off temprature at 20% of methane conversion was roughly 400 deg C.These preliminary results suggest that these ystems might be suitable for both low and high temprature applications.