Degussa Aktiengesellschaft

Degussa - Huls Ag

Umicore Ag & Co Kg

Evonik Degussa Gmbh

Lichner, Oskar

Lehmann, Thomas

Thomas Lehmann

Robert Schwarz

Karl-Anton Starz

Andreas Freund

Patrik Stenner

Emmanuel Auer

Gerhard Heinz

Christoph Weckbecker

Udo Stenke

Rainer Sanzenbacher

Dieter Engel

Edgar Koberstein

Thomas Tacke

Reinhold Brand

Ralf Zuber

Martin Hateley

Knut Fehl

Jürgen Bilz

Johannes Ohmer

Walter Behl

Armin Bayer

Sandra Olivero

Harald Troll

Jutta Lang

Volker B&auml;nisch

Andreas K&uuml;ver

Elisabeth Dunach

Christian Reufer

Oskar Lichner

Patrick Stenner

A process for the preparation of &#x3b1;-substituted carboxylic acids from the series including &#x3b1;-hydroxycarboxylic acids and N-substituted-&#x3b1;-aminocarboxylic acids by cathodic carboxylation with carbon dioxide of a compound corresponding to the general formula R&#x2014;C(&#x2550;X)Rwhich is constituted by aldehydes, ketones or N-substituted imines. In the past, that carboxylation has taken place in an undivided electrolytic cell with the use of a sacrificial anode. As described herein, the carboxylation takes place in the absence of a sacrificial anode in an electrolytic cell divided by a separator, at a diamond film cathode. The anode is formed of a material which is stable under electrolytic conditions; in particular, it is a diamond film electrode. The catholyte includes an organic solvent and a conducting salt.

Process for the preparation of &#x3b1;-substituted carboxylic acids from the series comprising &#x3b1;-hydroxycarboxylic acids and n-substituted-&#x3b1;-aminocarboxylic acids

A gas diffusion structure for polymer electrolyte fuel cells having a sheet-like carbon substrate made hydrophobic and having two main opposing surfaces and a contact layer on one of these surfaces. The contact layer is formed of an intimate mixture of at least one hydrophobic polymer, which can be polyethylene, polypropylene or polytetrafluoroethylene, and finely divided carbon particles, wherein the weight percentage of the carbon particles relative to the total weight of the contact layer amounts to 40 to 90 wt. %. The gas diffusion structure is a carbon substrate made hydrophobic by at least one hydrophobic polymer and the hydrophobic polymers are restricted to two layers extending from both opposing surfaces into the carbon substrate down to a depth of from 5 to 40 &mgr;m and the hydrophobic polymers fill of from 20 to 60% of the pore volume within those layers.

Gas diffusion structures and gas diffusion electrodes for polymer electrolyte fuel cells

A process for the electrochemical preparation of hydrogen peroxide, in particular an aqueous hydrogen peroxide solution, by the electrochemical reaction of oxygen and hydrogen in a fuel cell. By increasing the thickness of the membrane layer in a membrane electrode unit (MEU) in the fuel cell, it is possible to substantially increase the concentration of H O in the aqueous hydrogen peroxide solution obtained at the cathode.

Process for the electrochemical preparation of hydrogen peroxide

The invention relates to a process for the production of a peroxodisulfate, such as ammonium-, sodium- and potassium peroxodisulfate by anodic oxidation of an electrolyte containing a sulfate and/or hydrogen sulfate. The disadvantages of the conventional platinum anodes used for this hitherto can be avoided by using as the anode a diamond film mounted on a conductive carrier and made conductive by doping with a tri- or pentavalent element and by not adding a promoter to the anolyte.

Process for the production of alkali metal- and ammonium peroxodisulfate

A process for the production of 2-hydroxy-4-methylmercaptobutyric acid (MHA) by electrochemical carboxylation of 3-methylmercapto-propionaldehyde in an undivided electrolytic cell containing a sacrificial anode, in an aprotic solvent in the presence of a supporting electrolyte. Preferred anode/cathode combinations are Mg/Mg and Mg/carbon. MHA is obtainable in a high yield.

Process for the production of 2-hydroxy-4-methylmercaptobutyric acid

An electrolysis cell for carrying out chemical reactions include an electrolyte chamber (,) with a fixed-bed electrode (,F), a gas chamber (,) filled with filling bodies (,F), a gas diffusion electrode with an ion-exchanging separator (,) applied on the electrolyte-chamber side. The ion-exchanging separator is applied onto the gas diffusion electrode by a method comprising a single or multiple application of a solution of an ion-exchanging material in a solvent onto the electrocatalytically active layer of the gas diffusion electrode and at least partial evaporation of the solvent after each coating. The electrolysis cell may be used for the oxidation and reduction of organic or inorganic components dissolved in the electrolyte.

Electrolysis cell

A platinum alloy catalyst on an electrically conductive carbon support which contains an alloy of 40 to 60 atom-% of platinum, 10 to 20 atom-% of rhodium and 20 to 50 atom-% of iron in the form of finely divided alloy particles. The catalyst is characterised in that the average particle size of the alloy particles is less than 10 nm.

Pt/Rh/Fe alloy catalyst for fuel cells and a process for producing the

An electrolysis cell with a fixed-bed electrode and its use for the purification of waste gases. The electrolysis cell includes a fixed-bed electrode, a counterelectrode which is separated from it and designed as a gas diffusion electrode, devices for the supply and flow-off of an electrolyte as well as for the inlet and outlet of the gas to be purified and a space associated with the counterelectrode with devices for the supply and the removal of a gas. In order to purify gas the fixed-bed electrode is operated as a trickle bed and the gas to be purified flows in cocurrent or countercurrent flow to the electrolyte. In reductive purification hydrogen is supplied to the gas diffusion electrode and in oxidative purification oxygen is used.

Electrolytic method for purifying gases

A platinum/ruthenium alloy catalyst that includes finely dispersed alloy particles on a powdery, electrically conductive carrier material. The catalyst is particularly resistant to carbon monoxide poisoning when the alloy particles display mean crystallite sizes of 0.5 to less than 2 nm.

Anode catalyst for fuel cells with polymer electrolyte membranes

A platinum supported catalyst is disclosed for the anode in a PEM fuel cell with high resistance to poisoning by carbon monoxide. The catalyst contains the noble metals platinum and ruthenium on a finely divided, conductive support material. The two noble metals are not alloyed with each other and are present in highly dispersed form on the support material, wherein the crystallite size of the platinum is less than 2 nm and that of the ruthenium is less than 1 nm.

Co-tolerant anode catalyst for PEM fuel cells and a process for its

A process for the electrolytic removal of contaminants from gases, wherein a gas and a liquid electrolyte are passed co- or counter-currently through a fixed bed electrode of an electrolysis cell which has a counterelectrode separated from the fixed bed electrode by a separator and the contaminant is electrochemically converted at an effective cell voltage. Such cells have hitherto been operated in a flooded state. The degree of purification may be substantially increased if the fixed bed electrode is operated as a trickle bed reactor.

Process for the purification of gases

A catalyst for use in a fuel cell containing a platinum-aluminum alloy on a conductive carbon carrier, wherein the atomic ratio of platinum to aluminum is from 80:20 to 60:40 and the alloy is present on the carbon carrier in carbidized form with the structure of platinum-aluminum carbide Pt.sub.3 AlC.sub.0.5. Also disclosed are multimetallic alloy catalysts for use as electrode catalysts in fuel cells. Catalysts with high activity and stability are obtained on the basis of carbidized platinum-aluminum alloy catalysts by adding alloying elements of the groups VIB, VIIB, VIII and IB of the Periodic Table of Elements.

Platinum-aluminum alloy catalyst for fuel cells and method of its

A ternary platinum alloy catalyst on a conductive carbon carrier for use in fuel cells is disclosed. For the production of the catalyst, nitrate salts are used as precursors of the alloy components and all alloy components are deposited concurrently on the carbon carrier. This method of procedure yields ageing-stable catalysts with high oxygen mass activity.

Platinum alloy catalyst for fuel cells and method of its production

There is described the working up of a solution by electrodialysis originally prepared by the enzymatic resolution of an N-acetyl-DL-aminocarboxylic acid. The electrodialysis device used consists of a plurality of three-chamber packets, each of which comprises a feed and diluent chamber (1), a (basic) concentrate chamber (2) located on its cathode side and an (acidic) concentrate chamber (3) located on its anode side, whereby each three-chamber packet is separated from each of the two adjacent ones by a device (4) in which water is decomposed into OH.sup.- ions and H.sup.+ ions. The added resolution solution is separated by this device into three solutions, the first of which contains the L-amino acid, the second of which contains the cations present in the resolution solution as hydroxides and the third of which contains the anions present in the resolution solution as free acids.

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Langenselbold, Germany

Thomas Lehmann