Oxidative dehydrogenation of isopropyl alcohol on mixed tin and antimony oxide catalysts
TL;DR: In this article, it was shown that this mixed oxide system predominantly functions as Sb2O4 which is formed as a two-dimensional layer on the tin oxide matrix, at low concentrations of antimony and at low temperatures the solid solution-antimony oxide interface may be responsible for the observed activity.
About: This article is published in Surface Technology.The article was published on 1984-01-01. It has received 2 citations till now. The article focuses on the topics: Antimony oxide & Tin oxide.
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TL;DR: In this paper, the characteristics of selective oxidation on mixed tin and antimony oxide catalysts with special reference to the solubility limit, the role of the matrix, the nature of the active sites and role of acid-base sites are evaluated from an analysis of data reported in the literature.
7 citations
TL;DR: In this paper, X-ray 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.
Abstract: 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 .
6 citations
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TL;DR: In this paper, the X-ray photoelectron spectroscopy (XPS) line shapes showed that two phases may exist at the surface of the catalytic phase of the catalyst.
150 citations
TL;DR: The tin-antimony oxide catalyst is one of the most widely used catalysts for catalytic applications as discussed by the authors, and has been successfully used for the oxidation of propylene to acrolein and for ammoxidation of butenes to 1,3-butadiene.
Abstract: Publisher Summary This chapter examines tin-antimony oxide catalyst which has been commercially developed for the oxidation of propylene to acrolein as well as for the ammoxidation of propylene to acrylonitrile and the oxidative dehydrogenation of butenes to 1,3-butadiene. The tin-antimony oxide catalyst is one that is most amenable to investigation by a wide range of spectroscopic and physical techniques. The properties of the system are very sensitive to composition, calcination temperature, and length of treatment. It is shown in the chapter that the coprecipitated catalyst is an initially homogenous and amorphous solid, which is slowly crystallized on heating. It seems that the range of compositions which give rise to the formation of solid solutions is small and only occurs when the materials are heated to high temperatures. The cationic species in the solid solution phase of antimony in tin oxide appear to be antimony and charge balance seems to be achieved by the delocalization of electrons into a conduction band.
57 citations
TL;DR: A series of tin + antimony mixed oxide powders, calcined at 773 K, has been studied by electrical conductivity as discussed by the authors, and a continuity in the electrical behaviour is found between semiconducting SnO2 and insulating Sb2O4.
Abstract: A series of tin + antimony mixed oxide powders, calcined at 773 K, has been studied by electrical conductivity. A continuity in the electrical behaviour is found between semiconducting SnO2 and insulating Sb2O4. Pure stannic oxide is an n-type semiconductor and its free electrons come from the first ionization of anionic vacancies whose concentration is ≈ 1018 cm–3 at 608 K under 2.13 × 104 Pa O2. The enthalpy of formation of these vacancies and the ionization energy of their 2nd electrons have been estimated. As the Sb content increases, antimony dissolves into the SnO2 structure in the 5+ state, which increases the conductivity, σ, up to a maximum corresponding to 6.1 Sb atom %. Around this value formation of the Sb2O4 phase begins. The increased conductivity of mixed oxides with high Sb content (>20 atom %), compared with that of Sb2O4, which is an insulator, is attributed to a doping effect by Sn4+ cations in Sb3+ lattice positions of Sb2O4. Comparison of how both σ and catalytic properties vary with Sb content shows that electron transfer between catalyst and adsorbed species is not the rate limiting step in propene oxidation and that the solid solution of Sb5+ in SnO2 cannot constitute the active phase for acrolein formation.
45 citations
TL;DR: In this paper, mixed oxides of tin and antimony were investigated by X-ray diffraction and Mossbauer spectrometry as a function of chemical composition and of firing temperature.
Abstract: Mixed oxides of tin and antimony were investigated by X-ray diffraction and Mossbauer 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.
35 citations
TL;DR: In this paper, the X-ray patterns of the binary system after sintering were investigated and it was found that the color of the catalyst is closely connected with the formation of acrolein.
Abstract: For the purpose of elucidating the catalysis of the binary system consisting of Sn and Sb oxides, recommended in the patent for the oxidation of propylene to acrolein, the oxidation of propylene has been studied; in addition, the X-ray patterns of the system have been investigated. The mixtures of this binary system after sintering were different in color according to the catalyst composition and the calcination conditions. It was found that the color of the catalyst is closely connected with the formation of acrolein, and also that the blue-colored catalysts are effective in the selective production of acrolein. The pure tin oxide catalyst yielded mainly carbon dioxide and monoxide, while the pure antimony yielded scarcely any product. However, a selectivity to acrolein of more than 70% was obtained at 450°C over a catalyst with an optimal composition, for example, one with a Sn to Sb atomic ratio of 3 : 1 which had been calcined at 1000°C for 3 hr. The formation of acrolein was investigated as a functio...
32 citations