Basf Aktiengesellschaft

Norbert Neth

Christopher William Rieker

Manfred Stroezel

Klaus Volkamer

Ulrich Wagner

Michael Baier

Hermann Petersen

Michael Jolyon Sprague

Ruprecht Meissner

Otto Hofstadt

Otto Kumberger

Hans Christoph Horn

Wolfgang J&uuml;rgen P&ouml;pel

Wolfgang Buchele

Wolfgang Jurgen Popel

Dietrich Luetzow

Marco Millies

Production of solids by precipitation

Method of producing selective-dehydrogenation catalysts, and catalysts

Catalysts for the oxidation of sulfur dioxide to sulfur trioxide, consisting of a silica-based carrier and, applied on this, an active substance containing vanadium and alkali metal compounds, are prepared by dissolving vanadium pentoxide in an alkali solution, acidifying the solution with sulfuric acid, mixing the acidified solution with the carrier, molding the mixture and drying and calcining the molding. To obtain mechanically stable catalysts, a dissolved alkali metal silicate and/or silica sol are added to the alkaline solution before acidification, the latter process is carried out at below 35.degree. C. and the solution is then immediately incorporated into the carrier. The resulting moist crumbly material contains from 2 to 6% by weight of V.sub.2 O.sub.5, from 35 to 45% by weight of H.sub.2 O and from 15 to 50% by weight of SiO.sub.2. From 5 to 25% by weight of the total silica content originates from the dissolved alkali metal silicate and/or silica sol.

Preparation of a catalyst for the oxidation of sulfur dioxide to sulfur

A process for the manufacture of symmetrical dialkylureas by reacting monoalkylamines with CO.sub.2 at an elevated temperature and under superatmospheric pressure, in which the unconverted starting materials, water and the by-products formed in the reaction zone, as well as alkylamine alkylcarbamate, after thermal decomposition into monoalkylamine, CO.sub.2 and water, are separated from the dialkylurea formed, and thereafter a part of the unconverted starting materials plus by-products, with or without water, may or may not be recycled to the reaction zone, before isolating an aqueous solution, containing monoalkylamines, CO.sub.2 and other by-products, which solution is treated with alkali metal hydroxide solution in a column, the monoalkylamine, after separation from carbon dioxide and water, being recycled to the reaction zone. The dialkylureas obtained contain not more than 1% of monoalkylurea and 1% of trialkylurea, and may be used as starting materials for various syntheses.

Manufacture of symmetrical dialkylureas

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Bobenheim-Roxheim, Germany

Norbert Neth