1,720,974 research outputs found
Relationship between the zirconia-promoted reduction in the Rh-loaded Ce0.5Zr0.5O2 mixed oxide and the Zr-O local structure
No full textRh/CeO2-ZrO2 mixed oxides show improved redox properties compared to Rh/CeO2 due to a low-temperature reduction in the bulk. In the present work we have investigated the Zr-O and Ce-O local structure in Rh/Ce0.5Zr0.5O2 by means of EXAFS and Raman spectroscopy. By introducing Zr4+ into the CeO2 lattice, the oxygen sublattice is strongly modified compared to the ideal fluorite structure of CeO2: the Ce4+ ions retain their coordination while the number of oxygens around the Zr4+ decreases from 8 to 6 due to a displacement of two oxygens to a nonbonding distance. It is suggested that this distortion of the oxygen sublattice generates some mobile oxygens in Rh/Ce0.5Zr0.5O2 which are responsible for the improved redox properties
Resolution of a Structural Disorder through Apparently Inconsistent X-ray Diffraction and EXAFS Data: Structure of the New Layered System Mn1-xCu2xPS3 (x = 0.13)
No full textEXAFS Data Analysis of Vitamin B12 Model Compounds: a Methodological Study
No full textEUR. J. INORG. CHEM
CHARACTERIZATION AND CATALYTIC PERFORMANCES OF ALKALI-METAL PROMOTED Rh/SiO2 catalysts for propene hydroformilation
No full textEXAFS Determination of the Coordination Environment of the Metal in the Homogeneous Anionic (NCCH2Co(COOCH3)(CO)3)- Carbonylation Catalyst,
No full text
Relationships between Structural/Textural Properties and Redox Behavior in Ce0.6Zr0.4O2 Mixed Oxides
No full textThe redox behavior and the structural properties of Ce0.6Zr0.4O2 mixed oxides of high surface area and dense ceramic-type materials are compared. It is shown that due to the insertion of ZrO2 into the CeO2 lattice the oxygen sublattice becomes significantly distorted: Zr-O coordination of the type 5 + 2 and 4 + 2 is found in the former and latter samples, respectively. The nature of these distortions is correlated with the origin of the sample and it appears also to be related to the particle size of the Ce0.6Zr0.4O2 mixed oxide. Noticeably, the reduction behavior of these samples as investigated by the temperature-programmed reduction method appears correlated with their structural properties
Redox properties-local structure relationships in the Rh-loaded CeO2-ZrO2 mixed oxides
No full textThe local structure of the M-O bond in CeO2-ZrO2 mixed oxides is investigated with the aim of finding a correlation between structural parameters and oxygen exchange properties. It is found that insertion of ZrO2 into the CeO2 lattice strongly perturbs the symmetry of the M-O bond. As the content of CeO2 in CeO2-ZrO2 solid solution is increased from 20 to 80 mol%, tetragonal, (t, t′, t′′) and cubic phases are formed. The local symmetry of the Zr-O bond is strongly perturbed by the increase in CeO2 content while no significant modification of the first Ce-O coordination sphere is found, except for lengthening of the Ce-O bond consistent with lattice parameter increase. The perturbation of the Zr-O coordination sphere, which leads to highly disordered oxygen in the lattice, is indicated as responsible for the high oxygen mobility in CeO2-ZrO2 mixed oxides
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