Abstract: SiO2—TiO2 glasses having a low coefficient of thermal expansion are produced by a molding being produced that consists of SiO2 powder, SiO2—TiO2 powder or TiO2 powder and that contains by way of secondary component a titanium-containing component which is converted into amorphous TiO2.

Abstract: Pyrogenically prepared silicon dioxide with the following physicochemical properties:

Abstract: Pyrogenically prepared silicon dioxide with the following physicochemical properties: 1. Average particle size (D50 value)D50≧150 nm (dynamic light scattering, 30 wt %) 2. Viscosity (5 rpm, 30 wt %) &eegr;≦100 m·Pas 3. Thixotropy of Ti (&eegr;(5 rpm))/(&eegr;(50 rpm))≦2 4. BET surface area 30-60 m2/g 5. Compacted bulk=100-160 g/L 6. Original pH≦4.5 can be used for the preparation of dispersions and glass bodies.

Abstract: Aqueous dispersion comprising silicon/titanium mixed oxide powder with a BET surface area of 5 to 500 m2/g which has been prepared by flame hydrolysis and has a titanium dioxide content of 0.5 to 20 wt. %, based on the powder, water and at least one pH-regulating substance which can be removed completely from the reaction mixture on heating, the aqueous dispersion having a solids content of between 40 and 80 wt. %. A green body produced therefrom with a green density of between 40 and 85%. A shaped glass article of optical quality with a coefficient of thermal expansion of not more than 0.5×10−6/K produced from the green body.

Abstract: A product obtained by treating surface-modified, pyrogenically produced titanium dioxide with at least one ammonium-functional silane, such as by spraying the pyrogenically produced titanium dioxide with the at least one silane, alone or in ethanol solution, and tempering, and useful in the field of cosmetics in sunblocks, in toner powders, in paints and varnishes, in silicone rubber, as abrasives and polishes, for example, in the field of CMP.

Abstract: A layer which is obtained by thermal treatment from an aqueous dispersion applied to a substrate, the dispersion containing silicon/titanium mixed oxide powder prepared by flame hydrolysis. It is prepared by applying a dispersion which contains the silicon/titanium mixed oxide powder to a substrate and then sintering by using a thermal treatment. It can be used, for example, on materials with very low coefficients of expansion.

Abstract: Nanoscalar, pyrogenically produced yttrium-zirconium mixed oxide which has a BET surface area of between 1 and 600 m2/g, a total chloride content of less than 0.05 wt. % and does not exhibit a conversion into the monoclinic phase during storage is produced by atomizing yttrium compounds and zirconium compounds and reacting them in a flame. The mixed oxide can be used as ceramic raw material.

Abstract: A silicon-aluminum mixed oxide produced by flame hydrolysis and having a composition of from 1 to 99.999 wt. % Al2O3, the remainder being SiO2, which mixed oxide exhibits an amorphous structure in the X-ray diffraction pattern and consists of intergrown primary particles, and in these primary particles crystallites are present. These crystallites having sizes of between one and 200 namometers and the specific surface of the powder being between 5 and 300 m2/g. These products are produced by a process wherein silicon halide and aluminum halide are vaporized in a particular ratio to one another and are homogeneously mixed with air, oxygen and hydrogen in a mixing unit by means of any carrier gas, this mixture undergoes combustion in a burner of known construction and, after the separation of the solids from the vapour phase, any traces of halide possibly adhering to the product are separated off in a further processing step by means of moist air at elevated temperature.

Abstract: Pyrogenically prepared silicon dioxide with the following physicochemical properties:

Abstract: SiO2—TiO2 glasses having a low coefficient of thermal expansion are produced by a molding being produced that consists of SiO2 powder, SiO2—TiO2 powder or TiO2 powder and that contains by way of secondary component a titanium-containing component which is converted into amorphous TiO2.

Abstract: Granular products with individual granules with virtually spherical particles of a homogeneous density distribution are produced by converting solids into suspensions, atomizing the suspensions and drying them by sublimation drying.

Abstract: The stability of polymers against the action of heat and flames is improved in that a pyrogenically produced titanium dioxide containing iron oxide is added to the polymers.

Abstract: Compacts produced from a pyrogenically produced oxide, magnesium stearate, methyl cellulose and urea are mixed together in the presence of water, compacted, dried, comminuted to a powder, and the powder is pressed with an isostatic press to compacts and the compacts tempered. The resulting compacts have an outside diameter of 16 to 100 mm.

Abstract: Granules based on silicon dioxide and having the properties:Average particle size: 10 to 120 .mu.mBET surface area: 40 to 400 m.sup.2 /gPore volume: 0.5 to 2.5 ml/gPore size distribution: less than 5% of the total pore volume exists of pores with a diameter<5 nm, remainder are meso- and macroporespH value: 3.6 to 8.5Tapped density: 220 to 700 g/lThey are prepared by dispersing silicon dioxide in water, spray drying, and optionally heating and/or silanizing. The granules can be used as catalyst supports.

Abstract: Shaped, activated Raney metal fixed-bed catalysts are obtained by molding a powder of at least one catalyst alloy, comprising at least one Raney process metal as catalytically active component and a leachable alloy component, and a powder of pure Raney process metal as binder with the addition of a shaping aid and pore-producer and subsequent calcination at temperatures below 850.degree. C. During calcination the shaping aid and pore-producer are burned away. Catalyst alloy powder and binder powder thereby sinter together to give a mechanically stable and porous molded item. This molded item thus consists of particles of catalyst alloys which are bonded by the powder of pure Raney process metal. It has no catalytically inactive, ceramic or glassy binder. The surface layer of the molded item is activated by leaching the leachable alloy component contained in the catalyst alloys with caustic soda solution.

Abstract: A modified supported noble metal catalyst is disclosed for the selective hydrogenation of aromatic halonitro compounds to form aromatic haloamines. The support consists of active carbon. The active component is platinum modified with copper. The new catalyst is distinguished by good selectivity and a high yield.

Abstract: A sulphidized catalyst which contains platinum on activated carbon is described. The activity of the catalyst can be greatly improved, while retaining the same selectivity, when the platinum-containing impregnation solution contains an oxidizing agent.

Abstract: A process for uniform and reproducible impregnation of fixed bed catalyst supports in the form of loose particles with a desired shell volume, by applying atomized impregnating solutions of precursors of the catalytically active components onto the heap of catalyst supports circulated in a tank. By suitable selection of the spraying parameters, in particular the droplet size range, the quantity of solvent and the quantity of impregnating solution sprayed per rotation of the tank, the catalyst supports may be provided with shells with an excellent degree of uniformity.

Abstract: Apparatus for carrying out a method for the catalytic conversion of waste gases such as those which accumulate in the synthesis of vinyl chloride is presented in which the waste gases are successively treated at an elevated temperature with a catalyst for oxidative cracking and with a catalyst for oxidative afterburning.

Abstract: A process is described for preparing hydrogenation catalysts which contain noble metals, having at least one catalytically active component and optionally promoters and/or modifiers on a support consisting of activated carbon washed with nitric acid. The activated carbon is subjected to an oxidative pretreatment with an oxidizing agent before applying the catalytically active components, promoters and modifiers.