Basf Aktiengesellschaft

Hans-Juergen Becker

Matthias Schwarzmann

Wolf D Mross

Karl-Heinz Boehning

Juergen Plueckhan

Klaus-Christian Renner

Manfred Ohlinger

Werner Steck

Eberhard Koester

Werner Loeser

Christof Jaeckh

A silver catalyst containing lithium and cesium as promoters for the direct oxidation of ethylene with oxygen to give ethylene oxide is applied to a porous carrier and essentially consists of .alpha.-alumina and contains certain amounts of soluble calcium, aluminum, potassium and sodium salts. The carrier has a BET surface area of from 0.4 to 0.8 m.sup.2 /g, a pore volume of not less than 0.45 ml/g, the pores being equally accessible to cold and warm water, a bulk density of less than 700 kg/m.sup.3 and a shape which, in the reactor, provides a geometrical surface area of not less than 600 m.sup.2 /m.sup.3, on which more than 13% by weight of silver are applied as active component and more than 115 kg of silver are available per m.sup.3 of reactor, and from 100 to 300 ppm by weight of lithium and from 200 to 600 ppm by weight of cesium are present as promoters. A process for the preparation of the silver catalyst and its use for the oxidation of ethylene are described.

Silver catalyst and a process for its preparation

A silver catalyst for the direct oxidation of ethylene with oxygen to give ethylene oxide is applied on a porous carrier and essentially consists of .alpha.-alumina and contains certain amounts of soluble calcium, aluminum, potassium and sodium salts. The carrier has a BET surface area of from 0.2 to 0.8 m.sup.2 /g, a pore volume of not less than 0.5 ml/g, the pores being equally accessible to cold and warm water, and a bulk density of less than 650 kg/m.sup.3, and has a shape which, in the reactor, provides a geometric surface area of not less than 600 m.sup.2 /m.sup.3, on which more than 13% by weight of silver are applied as the active component, more than 110 kg of silver being available per m.sup.3 of reactor.

Silver catalyst and its preparation

A process for the manufacture of an acicular magnetic iron oxide containing from 0.5 to 10 percent by weight of cobalt and up to 24 percent by weight of divalent iron, each based on the amount of iron(III) oxide, wherein an aqueous suspension of gamma-iron(III) oxide, containing cobalt(II) and iron(II) ions, the suspension having a hydroxyl ion concentration of more than 3.6.times.10.sup.-6 moles/liter, is heated at from 50.degree. to 100.degree. C. for at least 15 minutes, and the resulting precipitate is filtered off, washed until neutral, dried at below 100.degree. C. and thereafter heated at from 100.degree. to 200.degree. C. The products thus obtained give, even when their cobalt content is low, a very high coercive force, while the effect of temperature on the coercive force and residual induction is very slight.

Manufacture of acicular cobalt-modified magnetic iron oxide

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Neustadt, Germany

Hans-Juergen Becker