Degussa Aktiengesellschaft

Degussa - Huls Ag

Degussa Aktienbesellschaft

Rudolf M Wagner

Robert S Nygren

Axel Kleemann

Matthias Creutz

Werner Groll

Stefan Nordhoff

J&uuml;rgen Glenneberg

Thomas Haas

Peter Werle

Rudolf Vanheertum

Wolfgang Merk

Harry Schiwiora

J&ouml;rg Sauer

Doris Hathaway

Stefan Gross

Manfred Stumke

Gernot Schock

Dieter M&ouml;ller

A process for the continuous preparation of very highly concentrated hydrogen peroxide having a content of greater than 80 wt.%, especially over 98 wt.%, by suspension crystallization and after-treatment of the H O crystals. The after-treatment takes the form of countercurrent washing in a hydraulic or mechanical washing column with a packed crystal bed. Hydrogen peroxide is disclosed having a concentration of from 99.9 to 100 wt.% and a content of TOC, nitrate, phosphate, nickel and tin of in each case less than 4 mg/l.

Crystallization process for producing highly concentrated hydrogen peroxide

A process for the concentration of aqueous hydrogen peroxide by discontinuous crystallization. A cooling surface is arranged in a crystallizing vessel and first wetted with hydrogen peroxide and then cooled at a high cooling rate, whereupon seed crystals form. The cooling rate is at least 1 K/s, preferably from 10 to 30 K/s. When the vessel has been filled with H O starting material, the latter crystallizes, starting from the seed crystals, and forms a crystal layer. When the mother liquor of lower H O concentration has been discharged, there follows a sweating operation with a slow increase in temperature, as a result of which the H O concentration in the crystal layer is increased further.

Process for the concentration of aqueous hydrogen peroxide by crystallization

In carrying out the hydrogenation stage of the anthraquinone process for the preparation of hydrogen peroxide in a hydrogenation reactor on a fixed bed catalyst of a particulate catalyst, the service life of the catalyst is increased in that the working solution comprising the reaction carrier and a gas phase comprising hydrogen, are passed through the hydrogenation reactor from the bottom upwards. The empty tube speed of the working solution is 0.05 to 100 m/h, preferably 10 to 50 m/h.

Process for the preparation of hydrogen peroxide

Palladium alloys consisting of (a) 65 to 85% palladium, (b) 0 to 10% gold and/or 0 to 5% platinum, (c) 0.1 to 10% tin, (d) 1 to 10% gallium, (e) 1 to 12% copper, (f) 0.05 to 1.5% ruthenium and/or 0.05 to 0.7% rhenium as well as (g) 0.01 to 4% tungsten and/or 0.01 to 4% aluminum and/or 0.01 to 4% zinc are use to produce firmly seated and removable dentures. These alloys do not form oxide films when melted in air.

Dentures and alloys for use in same

Economical but readily workable palladium alloys for baking on dental ceramics consist of 60 to 80% palladium, 0 to 8% gold, 0 to 5% platinum, 0 to 1% ruthenium and/or rhenium, 2 to 20% copper, 1 to 12% tin and/or indium, 0.2 to 5% of at least one of the elements tungsten, molybdenum, niobium, and tantalum, and 0 to 15% cobalt, with the proviso that the sum of tin and indium must be between 5 and 14%.

Use of silver-free palladium alloys for firing on dental ceramics

The production of 3-mercapto-propanediol-1,2 is attained with good yields and in an industrially simple manner by reacting liquid hydrogen sulfide with glycidol under pressure, namely either in the presence of aluminum oxide or a sodium aluminum silicate, i.e., in heterogeneous phase or in the presence of an alkali or alkaline earth hydroxide dissolving in reaction medium, i.e. in homogeneous phase.

Process for the production of 3-mercapto-propanediol-(1,2)

Guaiacol glycerine ether is obtained in very good yield and in very high purity by reacting glycidol with o-methyoxyphenol in the presence of an alkali hydroxide, an alkali alcoholate, an alkali cyanate or an alkali thiocyanate at 80.degree. to 150.degree. C. An especially effective purification of the crude product can be obtained by adding hydrogen peroxide, preferably prior to cooling.

Process for the production of guaiacol glycerine ether

The production of 1-amino-propanediol-2,3 is attained with good yields and in an industrially simple manner by reacting liquid ammonia with glycidol under pressure in the presence of a small amount of an organic solvent.

Process for the production of 1-amino-propanediol-2,3

The yield of 1-amino-propanediol-2,3 is greatly increased and the process is carried out in an industrially simple manner by reacting liquid ammonia with glycidol under pressure and in the presence of a small amount of water.

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Illertissen, Germany

Rudolf M Wagner