Sb Mixed Oxides Research Articles

Characterization of Sn-5at.%Sb mixed oxide catalyst studied by x-ray photoelectron spectroscopy and Auger electron spectroscopy

X-ray photoelectron spectroscopy and Auger electron spectroscopy analyses of an Sn-5at.%Sb mixed oxide catalyst showed that activation leads to an increase in concentration of antimony on its surface. This surface segregation is induced by the presence of oxygen in the gas phase. The active catalyst probably contains both antimony(V) and antimony(III) in addition to antimony(V) in solid solution with SnO 2.

Studies of the structural stability of Sn-Sb mixed oxide in the decomposition of isopropyl alcohol

Typical Sn-80at.%Sb mixed oxide undergoes structural reduction during the decomposition of isopropyl alcohol in the absence of gas phase oxygen, and the active phase may contain metallic tin and Sb 2O 3. However, in the presence of oxygen the catalyst retains its structural stability and acetone is the major product together with small amounts of CO 2 and propylene. Product inhibition studies with acetone reveal that oxidation of the acetone to CO 2 occurs in preference to oxidation of isopropyl alcohol. The effect of the partial pressure of isopropyl alcohol and the partial pressure of oxygen on the decomposition of isopropyl alcohol was investigated. The presence of a large excess of oxygen favours CO 2 formation, whereas smaller amounts of oxygen favour acetone formation. A possible mechanism for the reaction in the presence of gas phase oxygen is proposed.

Valence states and solubility limits in ternary iron-tin-antimony mixed oxide catalysts

The electrical conductivity study of a series of ternary Fe−Sn−Sb mixed oxides with 5 at. % Fe has shown that iron dissolves in the structure of SnO2 as ferric ions and, consequently creates acceptor centers which compensate the doping effect of Sb5+ ions simultaneously dissolved, thus increasing the maximum dissolution of pentavalent antimony and shifting thereby the apparition limit of Sb3+ ions towards higher Sb contents.

Influence of calcination on the electrical properties of tin-antimony mixed oxide catalysts

The electrical conductivity study of Sn−Sb mixed oxide powders is consistent with an enrichment in Sb (due to calcination) of the surface region where a solid solution of Sb in SnO2 and a Sb2O4 surface phase coexist.