Abstract
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.
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Original Russian Text © L.M. Plyasova, T.V. Larina, V.V. Kriventsov, V.I. Zaikovskii, E.V. Dokuchits, T.P. Minyukova, 2015, published in Kinetika i Kataliz, 2015, Vol. 56, No. 4, pp. 499–506.
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Plyasova, L.M., Larina, T.V., Kriventsov, V.V. et al. Effect of the Cr/Fe ratio on the structure of Fe-Cr-Cu-containing oxide catalysts. Kinet Catal 56, 493–500 (2015). https://doi.org/10.1134/S0023158415030167
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DOI: https://doi.org/10.1134/S0023158415030167