Effect of the Cr/Fe ratio on the structure of Fe-Cr-Cu-containing oxide catalysts
| Autor: | T. P. Minyukova, Vladimir I. Zaikovskii, Tatyana V. Larina, Vladimir V. Kriventsov, E. V. Dokuchits, L. M. Plyasova |
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| Rok vydání: | 2015 |
| Předmět: |
Extended X-ray absorption fine structure
Chemistry Inorganic chemistry Spinel Analytical chemistry Oxide chemistry.chemical_element General Chemistry Activation energy engineering.material Copper Catalysis Computer Science Applications law.invention Tetragonal crystal system chemistry.chemical_compound law Modeling and Simulation engineering Calcination High-resolution transmission electron microscopy |
| Zdroj: | Kinetics and Catalysis. 56:493-500 |
| ISSN: | 1608-3210 0023-1584 |
| DOI: | 10.1134/s0023158415030167 |
| Popis: | The morphology and structural and electronic states of nanodispersed copper ferrite-chromites of with different Cr/Fe ratios calcined at 900°C in an atmosphere of air were studied using a set of physical methods. The morphology, the homogeneity of chemical composition, and the degree of perfection of spinels formed from mixed Fe-Cr-Cu hydroxo compounds upon heat treatment were studied by HRTEM. From an analysis of atomic radial distribution curves, it follows that copper ferrite-chromite with a partially inverted spinel structure was formed at the ratio Cr/Fe = 1. With the use of DRS, it was found that all of the Fe-Cr-Cu-containing oxide samples contained Cu2+ cations in tetrahedral and tetragonally distorted octahedral oxygen coordination. In this case, the DRS spectra exhibited a decrease in the absorption energy of Cu2+ cations as the Cr/Fe ratio was decreased from 2 to 1, which indicated a decrease in the tetragonal distortion of the octahedral oxygen environment of the Cu2+ cations. In general, the data on the distribution of cations in Fe-Cr-Cu oxides with different Cr/Fe ratios obtained by EXAFS and DRS are consistent with the results of crystallochemical analysis. It was confirmed that the distribution of Cu2+ cations significantly affected the activation energy of water gas shift reaction. |
| Databáze: | OpenAIRE |
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