Showing papers on "Mixed oxide published in 1982"

Properties of the Solid Electrolyte Gadolinia‐Doped Ceria Prepared by Thermal Decomposition of Mixed Cerium‐Gadolinium Oxalate

Abstract: Fine-grained powder of the mixed oxide (CeO2)0.9(Gd2O3)0.1, which is an ionic conductor for oxygen ions, was prepared by coprecipitation of the corresponding oxalates followed by calcination. The powder was used to prepare pellets sintered at a relatively low temperature of 1000°C compared with the usual sintering temperature of 1700° to 1800°C. The size of the powder grains was determined from BET surface area (SBET) measurements. The effect of precipitation conditions and calcination temperature on Sbet was examined. The largest surface area measured was 88 m2/g. Decomposition of the oxalate powder was followed using an optical dilatometer. The decomposition was indicated by a large shrinkage and it was completed below 300°C (for a heating rate of 3.3°C/min). The formation of the oxide was verified by X–ray diffraction analysis. It shows that the product of decomposition is the oxide and that decomposition can be carried to completion at 250°C if the heating lasts for 1 h. The pellets had a density of 83% of theoretical, small grains (0.5 μm), and a conductivity which, at 900°C, is two–thirds of the conductivity of dense samples obtained from the same raw material, but calcined and fired at much higher temperatures.

Vanadium/phosphorus mixed oxide catalyst, process for its preparation and its use

Abstract: The invention relates to a vanadium/phosphorus mixed oxide catalyst, a process for its preparation and its use for the preparation of maleic anhydride. The catalyst according to the invention is prepared by reacting a vanadium(V) compound with phosphoric acid and/or a compound forming phosphoric acid with heating, optionally in the presence of water, and subsequently treating the product obtained after the reaction with organic solvents and/or diluents having reducing activity, optionally in the presence of a promoter, at an elevated temperature.

Preparation of improved mixed vanadium phosphorus oxide catalyst and their use in oxidation processes

Abstract: Vanadium phosphorus mixed oxide containing catalysts are prepared in an organic liquid reaction medium with heating wherein at least 1.5 moles organic liquid are removed from the reaction medium such as by distillation for each mole of vanadium which is reduced or reacted during such reaction and/or reduction. The resulting catalysts are useful for the production of maleic anhydride from 4 carbon atom hydrocarbons.

Thermally stable mixed oxide gels

Abstract: A process for cogelling a smectite with an inorganic metal oxide which is unstable with respect to retaining a high surface area, to produce a cogel of high surface area which has good retention of surface area at high temperatures. Suitable smectites for the practice of this invention are hectorite, chlorite, montmorillionite, beidellite, or admixtures of two or more of these materials with each other or with other materials, or the like. Exemplary of inorganic oxide gels suitable for the practice of this invention are the Group IV-B metal oxides, especially titanium oxide, and other metal oxides such as the oxides of thorium, uranium, silicon, aluminum, and the like.

Catalytic Oxidation of Propene

Abstract: The oxidation of propene on simple and mixed oxide catalysts to form various oxygen-containing products — acrylaldehyde, acrylic acid, acetone, and acetic acid — is surveyed, and the role of individual components of the active catalysts discussed. A list of 110 references is included.

Preparation of mixed vanadium phosphorus oxide catalysts and their use in oxidative processes

Abstract: Vanadium phosphorus mixed oxide containing catalysts are prepared by sequentially forming an alpha-VOPO, catalyst precursor in aqueous media, and thereafter partially reducing a portion of the vanadium to a valence state of +4 in an organic liquid reducing media, in the absence of corrosive reducing agents The catalysts exhibit excellent activity for the production of maleic anhydride from 4 carbon atom hydrocarbons such as n-butane

On the cayalytic properties of Sb-Sn mixed oxides

Abstract: Treatment of an Sb-Sn mixed oxide, calcined at 750 °C, with dil. HCl greatly improves the mild oxidation of propene to acrolein; it has been shown that large α-Sb2O4 particles, formed during the high-temperature calcination, do not favour this oxidation.

Catalytic preparation of hydrogen from carbon monoxide and water

Abstract: The shift reaction of carbon monoxide with steam to give carbon dioxide and hydrogen is carried out over a catalyst comprising iron oxide and at least one further metal oxide that is difficultly reducible to metal, contains metal exerting a valency of at least 2 and is incapable of forming a mixed oxide having the spinel structure M II M III 2 O 4 where M II is a divalent metal and M III is a trivalent metal.

Studies on the Thermal Decomposition of Pure and Mixed Hydroxides of Iron(III)—Nickel(II)

Abstract: The decomposition sequence of the pure and mixed hydroxides of iron(III) and nickel(II) containing 0–50 mol% of NiO and the formation of a ferrite phase have been studied using various experimental techniques. DTA plots of pure ferric hydroxide exhibit one endothermic peak at 130° and three exothermic peaks at 210°, 315° and 430°C. It has been confirmed by X-ray, IR spectroscopy and magnetic susceptibility measurements that the first exothermic peak corresponds to the crystallization of α-FeOOH while the second exothermic peak at 315°C corresponds to the formation of α-Fe2O3 and the third one is due to a change in crystallite size of the specimen.The positions of the endothermic peak at 130° and the two exothermic peaks at 210° and 315°C of ferric hydroxide do not vary significantly with the addition of NiO to the ferric oxide. However, there is a shift in the exothermic peak at 430°C. The magnetic measurements of the mixed oxide specimens indicate the possible formation of the ferrite phase within 550°C ...

Maleic anhydride catalyst recycle

Abstract: A catalyst for the oxidation of hydrocarbons comprising a phosphorus and vanadium mixed oxide wherein the catalyst prepared by using an organic medium can be recycled according to our process thus conserving up to ninety percent of the vanadium used in the preparation of the catalyst. The mixed oxide can also be promoted by a transitional element of the IV and V period of the periodic table. These catalysts are particularly useful for the oxidation of C4 hydrocarbons to maleic anhydride.

Catalysts based on iron, chromium, potassium and at least one rare-earth metal, their preparation and their use in dehydrogenation reactions

Abstract: Catalysts are described which contain iron, chromium, kaliophilite of formula Al2O3.2SiO2.K2O and potassium in excess in relation to that present in the kaliophilite, as well as at least one rare-earth metal or a rare-earth metal compound in a proportion, calculated as oxide, of 1 to 15 % by weight relative to the weight of the finished catalyst. The presence in the catalyst of a rare-earth metal oxide optionally at least partially precombined in the form of a mixed oxide, of perovskite or spinel type, with Fe, Cr, Co, Ni, Al or V, endows the catalyst with an improved activity and/or selectivity in dehydrogenation reactions of hydrocarbons, in particular of ethylbenzene to styrene.

Gas sensitive film and its manufacture

Abstract: PURPOSE:To lower operating temperature of an element without reducing sensitivity of the element by mixing ultrafine particle materials that have catalytic action and by making the resultant a mixed oxide ultrafine particle film when a single ultrafine particle film of a Sn oxide is formed. CONSTITUTION:By evaporating Sn in an O2 gas atmosphere and at the same time by evaporating Mn that is catalytic material, a gas sensitive film of a mixed oxide ultrafine particle where which an Sn oxide and an Mn oxide were mixed with an appropriate ratio is formed on a substrate. As for control for mixing ratio of a particle size of MnO ultrafine particle and mixing ratio for the ultrafine particle, a Sn-Mn alloy with desired ratio to be used as an evaporating source, and by controlling an evaporation condition such as an evaporation board temperature and a distance between an evaporation board and the substrate, Sn and Mn may be evaporated independently. A gas-sensitive film thus maked becomes to have sensitivity at about 50 deg.C, and at nearly 150 deg.C the maximum sensitivity. Further it operates at temperature lower by about 150 deg. as compared with a single ultrafine particles gas sensitive film of a Sn oxide.

A neutron diffraction investigation of the defect rutile structure of tin antimony oxide

Abstract: The defect structure of tin–antimony oxide has been investigated by profile refinement of powder neutron diffraction data. The structure, based on the occupation by antimony(III) of interstitial positions within the tin(IV) oxide rutile-type lattice, is described and the model used to rationalise some of the properties of the mixed oxide.