Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5370330 | Applied Surface Science | 2006 | 7 Pages |
Abstract
Antimony segregation is a common feature in Fe-Sb mixed oxides, which have been widely applied as catalysts in selective oxidation and ammoxidation reactions. This paper attempts to shed a light on the cause of such a common feature and on the nature of the antimony-enriched surface layer over FeSbO4 by means of XPS surface analysis. Single-phase FeSbO4 samples prepared by different methods were studied, and the antimony in their surface layer is a mixture of both Sb5+ and Sb3+ rather than single Sb5+. Their surface composition is close to FeSb2O6, which could be described as (FeSbO4)(Sb2O4)δ, δ = 0.5, and it is not “Fe(II)Sb(V)2O6” as suggested in literature. Fe-Sb mixed oxides with Sb/Fe > 1 (mol/mol) are mixtures of FeSbO4 and Sb2O4, and the surface of FeSbO4 grains would be a layer of (FeSbO4)(Sb2O4)δ, δ â¥Â 0.5. Fe-Sb mixed oxides with Sb/Fe < 1 are mixtures of FeSbO4 and Fe2O3, and the surface of FeSbO4 grains would be a layer of (FeSbO4)(Sb2O4)δ, δ â¤Â 0.5, but the remaining Fe2O3 would be encapsulated by a layer of FeSbO4.
Related Topics
Physical Sciences and Engineering
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Physical and Theoretical Chemistry
Authors
Yan Huang, Patricio Ruiz,