Degussa Aktiengesellschaft

Evonik Degussa Gmbh

Klaus-Dieter Hellwig

Juergen Schubert

Michael Pickel

Astrid Muller

J&uuml;rgen Schubert

Lothar Kaufmann

Hans-Dieter Puetz

Astrid Müller

Jürgen Schubert

The present invention provides a process, which includes:

Process for covering silicas with wax

Aluminum-doped precipitated silicas having a BET surface area of more than 300 m /g and aluminum distributed uniformly in the silica particles are prepared by sequentially heating a mixture of water and sodium silicate at a temperature of from 70 to 86&deg; C. and adding sulfuric acid until half of the sodium silicate is neutralized, then aging the mixture for a time of from 30 to 120 minutes, adjusting the pH of the mixture with sulfuric acid to a range of from 3.0 to 7.0, thereby precipitating the aluminum-doped silica, filtering the aluminum-doped silica from the mixture to form a filtercake and washing the filtercake, followed by drying and/or grinding the washed filtercake. An aluminum salt solution is metered into the mixture at step a) and/or step c). The aluminum-doped precipitated silicas of the present invention may be used in coatings for paper and other media intended for ink jet printing.

Doped precipitated silica

A method for the preparation of alkali metal selenates through oxidation of powdered selenium with hydrogen peroxide and neutralization of the formed selenic acid with alkali metal hydroxide or alkali metal carbonate, wherein the selenium oxide in the first step is brought to reaction at the surface of a warmed portion of hydrogen peroxide and subsequently in a second step the resulting acid solution is partially neutralized and the remaining selenite is further converted with hydrogen peroxide to the selenate.

Method for preparation of alkali metal selenates

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Bad Honnef, Germany

Klaus-Dieter Hellwig