Umicore Ag & Co Kg

Degussa Aktiengesellschaft

Peter Biberbach

Ulrich Baudis

Karsten Ruth

Marco Lopez

Wolfgang Weber

Karl-Anton Starz

Hans-Hermann Beyer

Andreas Schleunung

Ralph McIntosh

Emmanuel Auer

Andreas Gutsch

Edwin Staab

Michael Gross

Markus Pridöhl

Karl A Starz

Rainer Engelmann

The invention is directed to iridium oxide based catalysts for use as anode catalysts in PEM water electrolysis. The claimed composite catalyst materials comprise iridium oxide (IrO) and optionally ruthenium oxide (RuO) in combination with a high surface area inorganic oxide (for example TiO, AlO, ZrOand mixtures thereof). The inorganic oxide has a BET surface area in the range of 50 to 400 m/g, a water solubility of lower than 0.15 g/l and is present in a quantity of less than 20 wt. % based on the total weight of the catalyst. The claimed catalyst materials are characterized by a low oxygen overvoltage and long lifetime in water electrolysis. The catalysts are used in electrodes, catalyst-coated membranes and membrane-electrode-assemblies for PEM electrolyzers as well as in regenerative fuel cells (RFC), sensors, and other electrochemical devices.

Precious metal oxide catalyst for water electrolysis

The invention is directed to iridium oxide based catalysts for use as anode catalysts in PEM water electrolysis. The claimed composite catalyst materials comprise iridium oxide (IrO) and optionally ruthenium oxide (RuO) in combination with a high surface area inorganic oxide (for example TiO, AlO, ZrOand mixtures thereof). The inorganic oxide has a BET surface area in the range of 50 to 400 m/g, a water solubility of lower than 0.15 g/l and is present in a quantity of less than 20 wt. % based on the total weight of the catalyst. The claimed catalyst materials are characterised by a low oxygen overvoltage and long lifetime in water electrolysis. The catalysts are used in electrodes, catalyst-coated membranes and membrane-electrode-assemblies for PEM electrolyzers as well as in regenerative fuel cells (RFC), sensors, and other electrochemical devices.

The invention relates to a carbon-supported PtRu anode catalyst for direct methanol fuel cells (DMFC) which has a platinum/ruthenium content in the range from 80 to 98 wt. %, preferably in the range from 85 to 98 wt. %, particularly preferably in the range from 85 to 95 wt. % (based on the total weight of the catalyst), on a carbon-based electrically conductive support material and has a mean particle size of less than 3 nm. The catalyst is prepared using a carbon black support material having a specific surface area (measured by the BET method) in the range from 1000 to 2000 m/g by means of a reduction process using chemical reducing agents with addition of organic acids. Electrodes and membrane-electrode units containing the catalyst according to the invention having a high precious metal loading have an electrode layer thickness of less than 80 &#x3bc;m at a PtRu loading per unit area of the electrode of from 6 to 12 mg of PtRu/cmand lead to improved electric power in direct methanol fuel cells.

Platinum/ruthenium catalyst for direct methanol fuel cells

Process and apparatus for the thermal treatment of pulverulent substances, in which the pulverulent substance is dispersed in a carrier gas and is passed in a continuous manner through a heated reactor where it is thermally treated and is then quenched by a cooling medium and is collected in a gas-solids separating unit.

Process and apparatus for the thermal treatment of pulverulent substances

The invention provides a noble metal-containing supported catalyst which contains one of the noble metals from the group Au, Ag, Pt, Pd, Rh, Ru, Ir, Os or alloys of one or more of these noble metals in the form of noble metal particles on a powdered support material. The particles deposited on the support material have a degree of crystallinity, determined by X-ray diffraction, of more than 2 and an average particle size between 2 and 10 nm. The high crystallinity and the small particle size of the noble metal particles lead to high catalytic activity for the catalyst. It is particularly suitable for use in fuel cells and for the treatment of exhaust gases from internal combustion engines.

Noble metal-containing supported catalyst and a process for its preparation

The invention provides platinum or platinum alloy powders for use in fuel cells and for chemical reactions. The powders are characterized by a high surface area and, at the same time, low chlorine contents. The powders are prepared by forming a melt which contains, as starting substances, a low melting mixture of alkali metal nitrates, a chlorine-free platinum compound and optionally chlorine-free compounds of alloying elements, the melt is then heated to a reaction temperature at which the platinum compound and the compounds of alloying elements thermally decompose to give oxides, the melt is then cooled and dissolved in water and the oxides or mixed oxides formed are converted into platinum or platinum alloy powders by subsequent reduction. Binary or ternary eutectic mixtures from the LiNO &mdash;KNO &mdash;NaNO system are suitable as a low melting mixture of nitrates of the alkali metals. Hexahydroxoplatinic-(IV)-acid is preferably used as a chlorine-free platinum compound.

Platinum and platinum alloy powders with high surface areas and low chlorine content and processes for preparing these powders

The invention provides a process for preparing a platinum-ruthenium catalyst and the catalyst prepared therewith. The catalyst can be supported on a support material in powder form or may also be unsupported. To prepare the supported catalyst, the support material is suspended in water and the suspension is heated to at most the boiling point. While keeping the temperature of the suspension the same, solutions of hexachloroplatinic acid and ruthenium chloride are then added to the suspension, then the pH of the suspension is increased to a value between 6.5 and 10 by adding an alkaline solution and the noble metals are thus precipitated onto the support material. Afterwards, one or more organic carboxylic acids and/or their salts are added to the suspension and the catalyst is chemically reduced, washed, dried and optionally subsequently calcined under an inert or reducing atmosphere at a temperature between 300 und 1000&deg; C. The catalyst is characterised by a high tolerance to carbon monoxide poisoning in the fuel cell.

Process for preparing an anode catalyst for fuel cells and the anode catalyst prepared therewith

There is provided a crucible for containing salt baths for the boriding of steels which has a high service life made of a steel which consists of (or consists essentially of) 0.05-0.8% carbon, 0.8-2.5% silicon, 0.1-2.0% manganese, 0-1.5% aluminum, 6-30% chromium, 4-39% nickel and the balance iron.

Crucible for holding salt baths for the boriding of steels

There is described a salt bath based on an alkali and/or alkaline earth metal halide with which there can be produced without the use of current adherent and wear resistant boride coatings on metallic workpieces. This bath contains gaseous boron monofluoride or a compound from which there is formed intermediately boron monofluoride. Advantageous there is used a salt bath containing 30-60% BaCl.sub.2, 10-25% NaCl, 1-20% boron oxide or borate, 10-30% NaF, and 1-15% B.sub.4 C.

Salt bath for the currentless production of wear resistant boride layers

It is known to regenerate salt baths for nitriding parts of iron and steel with polymers of organic materials, which polymers, however, could not be used in carburizing salt baths since with them there only are formed slight amounts of carburizing active cyanide, the baths foam, and carbon residues are formed. An excellent regeneration agent for carburizing salt baths is obtained by using polymeric organic compounds of the overall composition [C.sub.6 H.sub.x N.sub.y ].sub.z where x is 3 to 5, y is 5 to 8, and z is 10 to 10,000. These compounds are obtained by reacting formaldehyde with cyanamide and/or dicyandiamide and/or melamine and pyrolytically decomposing the reaction product at 300.degree. to 600.degree. C.

Regeneration agent for carburization salt bath

For removing and dissolving sand mold residues from cast parts, particularly sand mold residues containing zirconium oxide and titanium oxide, there have previously been used mechanical and electrochemical processes in salt melts. However, these processes are very expensive, attack the surface of the cast pieces or fail to work with sand mold constituents which are difficult to dissolve. These disadvantages are avoided by inserting the cast parts having adhering sand mold residues into a melt of 55 to 97 weight % of alkali metal hydroxide and 3 to 45 weight % of one or more fluorides of an element of the first to third main group of the periodic system of elements and/or zinc at 400.degree. to 900.degree. C. Preferably the salt melt additionally contains a boron-oxygen and/or a boron-fluorine compound.

Process for removal of sand mold residues from cast parts

Vanadium carbide layers are produced on iron and iron alloys having a content of at least 0.1 weight % carbon by treating the workpiece at 800.degree. to 1100.degree. C. in a salt bath which contains 1-30 weight % of vanadium or ferrovanadium powder. The salt bath consists of alkaline earth and/or alkali metal halide.

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Rodenbach, Germany

Peter Biberbach