Structural properties of Sb–Sn—O mixed oxide catalysts
- 1 January 1980
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 76, 1652-1659
- https://doi.org/10.1039/f19807601652
Abstract
Mixed oxides of tin and antimony were investigated by X-ray diffraction and Mössbauer spectrometry as a function of chemical composition and of firing temperature. At low calcination temperatures, antimony is present as Sb5+ dissolved in the SnO2 lattice at 5 atom % Sb and a mixture Sb5++ Sb3+ at higher concentrations. Upon calcination a demixing of the solid solution occurs and an antimony oxide phase is formed. From X-ray diffraction, this phase is identified as a bidimensional Sb2O4 layer. The balance of electrical charges in the lattice is achieved by two different mechanisms as a function of the Sb content: delocalization of electrons in the conductivity band at low antimony content and reduction of Sb5+ to Sb3+ at higher antimony percentage. Good selectivities are obtained for propene oxidation when the system is biphasic; it is postulated that the actual catalyst consists of an oriented film of Sb2O4 supported by the Sb5+–SnO2 solid solution.Keywords
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