Huels Aktiengesellschaft

Chemische Werke Huls Aktiengesellschaft

Chemische Werke Huels Aktiengesellschaft

Huls Aktiengesellschaft

Helmut Scharf

Gerhard Franz

Wilfried Krix

HoGunther

1. Unstablized or stablized zirconium dioxide powder and processes for its preparation. 2.1 The use of aqueous solutions and the isolation of precipitates are substantial disadvantages of conventional processes for the preparation of zirconium dioxide powders. Furthermore, the products often do not have the desired flow properties, compression properties and sinter properties owing to the lack of microcrystallinity. 2.2 By melting zirconyl chloride optionally with a stabilizer or with a precursor of a stabilizer in the presence of a diol of the general formula HO--X--OH, in which X represents a saturated hydrocarbon radical having 2 to 5 carbon atoms, evaporating off water and hydrogen chloride, calcining the reaction product at elevated temperature in an oxygen-containing gas and optionally milling the calcined residue, an unstabilized or stabilized zirconium dioxide powder having good properties can be prepared without the use of disadvantageous process measures. 2.3 The unstabilized or stabilized zirconium dioxide powder is suitable for the production of sintered articles which can be subjected to high mechanical and/or thermal stresses.

Zirconium dioxide powder, processes for its preparation and its use for

Solids are fractionally desublimed in vapor form from a gas/vapor mixture by providing a nozzle through which a gas/vapor mixture containing a solid is accelerated, the nozzle being provided with a concentric opening which allows a cooling gas flowing laterally at a high velocity to impinge upon and mix with the gas/vapor mixture flowing through the nozzle in the mixing zone of the nozzle thereby forming a gas/solid mixture, passing the gas/vapor mixture through the nozzle and the cooling gas through the concentric opening such that the angle at which the cooling gas emerges from the concentric opening into the flow of the gas/vapor mixture to the direction of flow of the gas/vapor mixture ranges from 0.17 pi rad to 0.75 pi rad, the temperature of the resulting gas/solid mixture in the mixing zone being adjusted by the flow rate of the cooling gas in such a way that the temperature is below the sublimation temperature of the desired product solid but above the sublimation temperature of the by-products in the gas/vapor mixture, and allowing the gas/solid mixture to exit the nozzle in the direction of flow of the gas/vapor mixture through the nozzle.

Process and equipment for the fractional desublimation of solids in

For the non-clogging, fractional desublimation of vapor-phase solids contained in a gas-vapor mixture, the gas-vapor mixture, exiting at high velocity from a nozzle, is mixed with a cooling gas, likewise exiting at high velocity from another nozzle. The gas-vapor mixture and the cooling gas flow toward each other, the axes of the two gaseous streams being a straight line. Fractional desublimation of the solids is attained by adjustment of flows leading to the regulation of the temperature and residence time of the cooled gas-vapor mixture. This desublimation system is capable of degrees of efficiency and solids purities higher than 99%.

Process and apparatus for fractional desublimation of vapor-phase solids

A method for utilizing distillation residues of phthalic anhydride or maleic anhydride, which comprises: (a) cooling hot, liquid distillation residues of said phthalic anhydride or maleic anhydride while flowing as a stream in a first organic liquid; (b) comminuting said distillation residues solidifying in said first organic liquid by means of a cutting edge rotating at high rpm to produce a granulate; (c) suspending said granulate in a second organic liquid; and (d) incinerating the suspension or converting the suspension into synthesis gas.

Method of utilizing distillation residues of phthalic acid anhydride or

A method of separating pyromellitic acid dianhydride from the reaction gas obtained from the gas phase oxidation of 1,2,4,5-tetraalkylbenzene with an oxygen bearing gas in a closed gas circulatory system, comprising, (a) desublimating pyromellitic acid dianhydride by contacting the product gas obtained from said gas phase oxidation reaction with a cold, oxygen bearing gas, (b) catalytically burning the byproducts in the waste gas obtained from the desublimation step, and (c) recirculating a proportionate amount of the byproduct free waste gas to the oxidation reactor for the gas phase oxidation reaction.

Method for the manufacture of pyromellitic acid dianhydride

Isobutyraldehyde is produced by the oxo process and converted to acetone in the gas phase by oxidative decarbonylation on a zinc oxide supported copper oxide catalyst. The conversion is improved by adding about 2.5 to 25 percent by weight graphite to the catalyst, based on the total weight of catalyst.

Process for the production of acetone from isobutyraldehyde

This is an improvement in the process for preparing acetone by the catalytic, oxidative decarbonylation of isobutyraldehyde in the gaseous phase by passing a mixture consisting of isobutyraldehyde, oxygen and an inert diluent, when desired, at higher temperatures and at contact-times from 0.1 to 10 seconds over a carrier catalyst where the novel catalyst contains a mixture of copper oxide or manganese oxide, or a mixture thereof, with zinc oxide. A mixture comprising about 1 to 4.5 vol. % of isobutyraldehyde, about 1.2 to 99 vol. % of oxygen and an inert diluent, when desired, is passed over a catalyst at a temperature of about 130.degree. to 180.degree. C., consisting of about 0.1 to 6% by weight of Cu or Mn, or a mixture thereof, in the form of their oxides and of about 1 to 10% by weight of Zn in the form of zinc oxide on aluminum oxide as the carrier.

Process for preparing acetone from isobutyraldehyde

A process for improving the adhesion of isocyanate-crosslinked polyester coatings on vulcanized articles of ethylene-.alpha.-olefin-diene terpolymers, characterized in that the vulcanized articles, which contain at least 30 parts by weight of carbon black per 100 parts by weight of the ethylene-.alpha.-olefin-diene terpolymer, are treated with a compound having a functional group reactive with isocyanates and a carbon structure with at least 4 carbon atoms.

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Schermbeck, Germany

Helmut Scharf