Degussa Aktiengesellschaft

Umicore Ag & Co Kg

Degussa - Huls Ag

Degussa Aktiengesselschaft

Manfred Diehl

Roland Bergmann

Joachim Fischer

Hubert Wolf

Gunter Stadtmuller

Karl-Anton Starz

Wolfgang Leonhardt

Norbert Steiner

Gunter Prescher

Gerhard Morlock

Ralf Zuber

Karl-Hans Muller

Sandra Wittpahl

Thomas Lieser

Manfred Dankowski

Knut Fehl

Joachim Köhler

Maurizio Ragnetti

Juergen Loroesch

Karl-Heinz Koenig

Stephen Gos

Annette Ziegler

Wolfgang G&ouml;ttenauer

Frank Ladwig

Eckhart Krone

Jochen Ullmann

Friedhelm Brandner

Klaus Stuetzel

Udo Kittelmann

Hans-Jurgen Strempel

Sigrid Diener

Joachim Kohler

A process for producing a membrane electrode assembly for fuel cells containing a polymer electrolyte membrane having a first and a second surface parallel to each other. The first surface forms a firm composite with a first catalyst layer and a first water repellent gas distribution layer and said second surface form a firm composite with a second catalyst layer and a second water repellent gas distribution layer. The catalyst layers are prepared by using inks containing electrocatalysts, one or more solvents, proton-conducting ionomer and optionally water repelling agents and pore-forming agents. In the process the two catalyst layers are applied to or contacted with the respective surfaces of the polymer electrolyte membrane successively, wherein during the application or contacting process to one surface always the opposite surface of the membrane is supported.

Process for producing a membrane electrode assembly for fuel cells

A process is disclosed for applying electrode layers to a polymer electrolyte membrane strip in a desired pattern, wherein the front and back of the membrane are continuously printed with the electrode layers in the desired pattern using an ink containing an electrocatalyst, and the printed electrode layers are dried at elevated temperature immediately after the printing operation, the printing taking place while maintaining accurate positioning of the patterns of the electrode layers on the front and back in relation to one another.

Process for applying electrode layers to a polymer electrolyte membrane strip for fuel cells

A process is disclosed for the leaching of gold and silver from ores and ore concentrates through intimate contact of the ore or ore concentrate with an aqueous leach solution containing cyanide. The leach solution has a pH of 8 to 13. The leaching process takes place in the presence of an oxygen-releasing peroxo compound. The separation of the formed cyano complexes of gold and silver takes place in a known manner. During leaching, at least one peroxoborate compound is present, in an effective quantity, as the peroxo compound. The peroxoborate is preferably a sodium or calcium peroxoborate. Compared to previously known leaching techniques in the presence of hydrogen peroxide or calcium peroxide, the leaching process according to the present invention provides a higher and/or faster precious metal yield and/or minimizes the consumption of cyanide and/or oxidizing agent.

Process for leaching of precious metals

Reduction of the nitrite content of aqueous solutions by treatment with hydrogen peroxide in the acidic pH range can be controlled by measurement of the redox potential. Contrary to the teaching of the prior art, addition of the hydrogen peroxide in the process according to the invention is terminated not at the highest redox potential, but only after lowering of the potential to a value of 650.+-.10 mV. In this way, nitrite contents below 1 mg/l can be obtained even when the solutions additionally contain fluctuating amounts of various compounds oxidizable by H.sub.2 O.sub.2.

Process for automatically controllable reduction of the nitrite content

A process is disclosed for the detoxification of aqueous solutions containing cyanides and/or cyano complexes in the presence of heavy metals which are Mn, Co, Ni, Cu, Cd and Zn, more particularly Cu, by oxidative treatment of the solutions with peroxide compounds at pH values of 8 to 12. Peroxide compounds from the group consisting of alkali metal percarbonates and alkaline earth metal peroxides are used. The peroxide compounds are added to the solutions to be detoxified per se or are formed in situ therein from hydrogen peroxide and other components. Sodium perborate, sodium percarbonate and calcium peroxide are preferred.

Process for the detoxification of cyanide-containing aqueous solutions

A process is disclosed for the detoxication of aqueous solutions which contain cyanohydrins, in particular glycol nitrile, and/or nitriles and in addition contain decomposition catalyst for peroxide compounds, in particular manganese compounds, by perhydrolysis of the cyano compounds at temperatures of from 5.degree. to 80.degree. C. and pH values of from 8 to 12 by means of one or more peroxide compounds which are alkali metal percarbonates and perborates of alkali metals and alkaline earth metals and alkaline earth metal peroxides. The peroxide compounds are added as such to the solution to be detoxified or formed in situ in the solution to be detoxified. Sodium percarbonate is preferably used.

Process for the detoxification of aqueous solutions containing

A process is disclosed for the separation of hydrogen cyanide from gases and waste gases by a throughflow or circulation scrubbing, in which formaldehyde is added at a controlled rate to the aqueous scrubbing liquid to form glycol nitrile. This addition is controlled by measuring the HCN tension in a measuring stream which has been branched off and which is first treated with hydrogen peroxide so that free H.sub.2 O.sub.2 is still detectable after 1 to 100 seconds and the pH is adjusted to a constant value before measurement of the HCN tension is carried out. The process prevents overdosing with formaldehyde which could not always be prevented in previously known processes in which the addition of formaldehyde was regulated by measuring the cyanide specific redox potential.

Process for the separation of hydrogen cyanide from gases and waste gases

A stable, pumpable, aqueous solution of a water-insoluble silicate capable of binding calcium ion is shown which, referred to the total weight of the aqueous suspension, contains

Stable aqueous suspensions of detergent zeolites and four oxo-alcohol

The detergent builder consists of a water-insoluble silicate capable of binding calcium ions as well as of a mixture of two acrylic acid polymerizates which exhibit different viscosity numbers.

Phosphate-free detergent builders

Granulated detergent builders, are disclosed consisting essentially of:

Water-insoluble silicate containing detergent builder granulate

Aqueous bleaching agent suspensions based on a water-soluble peroxycarboxylic acid suspended in a carrier liquid in the presence of an organic thickening agent and of an acidifying agent exhibit an improved storage resistance over known suspensions with this base. This is achieved by means of pourable to pasty bleaching agent suspensions which contain a xanthan polysaccharide or agar polysaccharide as thickening agent and, in addition, a hydrate-forming neutral salt which desensitizes peroxycarboxylic acids. Preferred suspensions exhibit a pH of 2-5 and contain 10-30% by wt. diperoxydodecanedioic acid, 5-20% by wt. sodium sulfate and 0.1-1.0% by wt. xanthan. The use of non-dried, hydrophilized and optionally in situ desensitized peroxycarboxylic acids is especially preferred. The bleaching agent suspensions are prepared by homogeneously suspending the peroxycarboxylic acid in the thickened carrier liquid. The storage-resistant bleaching agent suspensions are used as laundry bleaching agents and for preparing cleaning agents and disinfection agents.

Aqueous bleaching agent suspensions containing peroxycarboxylic acid,

There is prepared an aqueous stable suspension of a water insoluble silicate capable of binding calcium ions and it is used for the production of washing and cleaning agents. The suspension contains in addition to water components A and B wherein component A is a silicate capable of binding calcium and having the formula

Aqueous stable suspensions of water insoluble silicates capable of

A granulated detergent builder is disclosed comprising:

Detergent builder

A laundry softener concentrate comprises one or more laundry softeners, synthetic silicon dioxide, and optionally one or more solubilizers. The laundry softener concentrate is in the form of a flowable powder.

Laundry softener concentrate

A scouring powder is provided which contains as the sole mechanical cleaning component crystalline zeolite powder of Type A having the following particle spectrum:

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Frankfurt-am-Main, Germany

Manfred Diehl