Kernforschungsanlage Julich Gesellschaft MIT Beschrankter Haftung

Kernforschungsanlage Julich

Metallgesellschaft Aktiengesellschaft

Jiri Divisek

Jurgen Mergel

Heinz Schmitz

Peter Malinowski

Bertel Kastening

Wolfgang Faul

Leander Furst

Heinrich Schmitz

Heinz Wullenweber

Bernd D Struck

Heiko Barnert

Harald Luft

Renke Hesse

Frans G Bodewig

Porous electrodes are obtained by a method in which a layer of a powder mixture comprising (a) finely divided carbonyl metal having a low bulk density and high frictional resistance and (b) a pulverulent component which is catalytically active or can be activated by alkali treatment, in an a/b ratio of about 3:1 to 1:3, is applied by rolling to one or both sides of a framework-forming metallic substrate having adhesion-promoting surface roughness, and said layer is consolidated by electrodeposition of metal, after which activation is finally effected if necessary. Superficial oxidation of the powder particles, which decreases from the outer surface of the layer toward the support and gradually dissolves in the electroplating bath, promotes extensive consolidation of the layer by electrodeposition.

Process for the production of porous electrodes

An electrolyzer for alkaline electrolysis of water has a diaphragm-electr sandwich arrangement wherein a predetermined narrow spacing to provide a minimum distance is maintained between the diaphragm surface and the superjacent electrode. The spacing is provided by a single layer of a filament of predetermined thickness disposed in an array. The filament is strung in a plurality of lengths disposed in a common plane so that the thickness of the spacing is the same as the thickness of the single layer which is equal to the filament thickness. The array is secured by a retaining wire which engages a groove provided in a cell frame of the electrolyzer. The filament is made of plastic material which can withstand electrolysis conditions. An apparatus and method for stringing the filament to provide the array are also described.

Electrolyzer with sandwich arrangement of diaphragm and electrodes and

In a process for reduction or oxidation of materials in aqueous solution by assing a reagent gas through a finely porous catalyst layer into the solution, bodies of electrically conducting material which in the aggregate have a large surface are brought into electrically conducting connection with the catalyst layer on its side facing the solution in order to increase the rate of conversion of the dissolved material. The conducting bodies are distributed in the solution at least in the region of the catalyst layer and increase the effective surface for the conversion of the dissolved material. The invention is particularly useful in connection with catalyst layers provided with an electrically conducting protective cover through which gas and solution may pass on the side of the catalyst layer facing the solution as disclosed in a related application of the same inventors Ser. No. 500,941 filed June 3, 1983.

Process for reduction or oxidation of materials in water solution by

A diaphragm for alkaline electrolysis, specifically for alkaline electrolysis of water, comprises a fine-pored, predominantly ceramic layer, which is preferably supported by a superficially oxidized structural framework or mesh. The diaphragm in use is sandwiched between two electrodes and is provided, on one or both sides, with fairly coarse-grained protuberances distributed over the surface and embedded into the fine-pored predominantly ceramic layer, which grains project out of the diaphragm surface. In view of the projection of the grains to form protuberances, and in spite of the fact that the adjacent electrodes are in contact with the diaphragm, a certain minimum distance is maintained between the diaphragm and each electrode, whereby, deposits on the electrodes, caused by unavoidable corrosion phenomena within the electrolysis apparatus, cannot propagate into the diaphragm. These coarse grains, about 10-250 microns in size, are thinly distributed over the diaphragm surface during the manufacture of the diaphragm before sintering, and are caused to be embedded in the surface with a slight application of pressure, so that they stick out in the form of 'nubs', resulting in reduced energy consumption during electrolysis.

Diaphragm for alkaline electrolysis and process for manufacture of

A process for the manufacture of thin activated electrodes including a base metal, which can be iron, cobalt or nickel, with a good adhering active surface layer. Both the base metal and the surface layer are galvanically sequentially deposited as separate layers on a removable electrically-conductive carrier. The surface layer is deposited as an activatable alloy including the base metal and a leachable metal, particularly zinc. The galvanizing deposited layers are subsequently separated as a unit from the carrier. The alloy is activated by leaching the leachable metal therefrom before, during or after separation of the carrier. Two activatable layers of alloy can be deposited on the carrier with a layer of the base metal deposited between the alloy layers.

Activated electrodes

The invention concerns a NiO-based ceramic oxide diaphragm for the alkaline water electrolysis. The diaphragm, in accordance with the invention, contains 0.5 to 10% by weight (estimated as Ti based on the oxide mass) of titanium oxide in the porous NiO layer. Diaphragms of this type are obtained, in particular, by the oxidative sintering of a mass of nickel powder which has been applied under pressure to a nickel support, especially one consisting of nickel wire gauze. In the process the titanium is in the form of titanium metal, titanium oxide or a titanium compound which is added to the initial nickel powder. The titanium is present in the form of its oxide after the oxidation sintering treatment. In an alternative embodiment of the process, an already sintered porous mass of nickel or nickel oxide can be impregnated with a titanium compound and calcined to convert the titanium compound to its oxide.

Nickel oxide based diaphragm

The invention is concerned with an electrochemical gas analyzer for determining the sulphur dioxide content of certain gases in particular, flue gases. The device comprises a measuring cell containing a measuring electrode for the determination of the depolarization current and further comprising an unpolarizable electrode in the same electrolyte. The gas input flow is utilized to cause a circulation of electrolyte containing the dissolved gas which moves in the space between the measuring and counter-electrode. The electrolyte is continuously renewed and the electrolyte leaving the cell is regeneratd and recycled. The sulphur dioxide dissolved in the electrolyte is removed outside the cell by treatment with air in the presence of activated charcoal.

Electrochemical gas analyzer for determination of sulphur dioxide

The invention concerns an electrolyzer for alkaline water electrolysis whose cells are formed by a diaphragm provided with electrodes between 2 bi-polar separator plates as well as a process for the construction thereof.

Electrolyzer for alkaline water electrolysis

A diaphragm of porous sinter material for alkaline water electrolysis characterized by a porous sinter metal oxidized at least partially to metal oxide. A frame structure of the sinter body is provided especially wire net. The base metal of the sinter body is formed by nickel, iron or copper. The method includes forming a porous metal sinter body and oxidizing the same at elevated temperature in oxygen-containing atmosphere. The method for production of nickel oxide diaphragms furthermore includes applying to a nickel net a pasty mass of nickel powder containing a binder and burning. Applying in a thin layer as by brushing nickel powder of a particle size of about 1 to 10 mm in a rubber solution in toluene upon a carrier, especially a nickel net, and this arrangement is subjected to sintering at 700.degree. to 1,000.degree. C. for a time or duration of 10 to 20 minutes in inert or reducing atmosphere especially in hydrogen and the sinter body which is obtained is subjected to roasting in air at 1000.degree. C. to 1200.degree. C. up to three hours, especially for a time duration in a range of between ten and forty minutes. The diaphragms are produced with a thickness in a range of approximately 1 mm, especially in a range of approximately 0.3 mm to 0.7 mm. Utilization of the diaphragm includes electrolysis cells with active porous nickel electrode fixed on the diaphragm in a sandwich manner of construction.

Diaphragms for alkaline water electrolysis and method for production of

A porous oxide diaphragm for alkaline electrolysis, in particular water etrolysis, consisting of an in situ oxidized metal powder layer applied onto a permeable framework-forming carrier without heat treatment before oxidation, as well as a process for the manufacture thereof and its utilization.

Porous oxide diaphragm for alkaline electrolyses, and manufacture thereof

A method for increasing the current yield or electrolytic efficiency of a sion electrolysis, especially water electrolysis, with which an anodic oxygen separation occurs. Lithium ions are added to the fusion electrolyte. Such lithium ions may be added by adding lithium as hydroxide or fluoride, sulfate or carbonate. The lithium addition amounts to at least 15 Mol % of the melt. Electrolyte is formed by a lithium hydroxide containing alkali hydroxide melt.

Method for increasing electrolytic efficiency of a fusion electrolysis

Particles of electrically conducting activated carbon of about 500 to 1,000 m.sup.2 /g specific surface added to an electrolyte provided by a solution of sulfur dioxide in water are found to provide a substantial reduction of the electrical energy requirement in the electrolysis of such an electrolyte for the production of hydrogen and sulfuric acid. A further reduction of energy consumption is obtained by additionally introducing iodine in the electrolyte in an amount not exceeding 1% by weight of the entire solution. Use of an anode in which the surface of a graphite base body is coated with a thin layer of activated carbon bonded to the graphite body by means of a binder, such as rubber, also reduces the electrical energy requirement for the electrolysis. To coat the surface of the electrode, carbon particles are first dispersed in a rubber solution and the suspension is then applied to the surface of the graphite body as a thin layer.

Process for the electrolysis of sulfur dioxide solutions

On a sheet steel carrier a suspension containing a binder and nickel powder r a powder containing a nickel alloy in a volatile suspension medium is applied, with or without an additional pore-forming material, and the sintered to produce a porous sintered layer. Alternatively, this sintered layer can be obtained by depositing and consolidating the powdered mixture on the carrier with the aid of a plasma gun. A nickel/zinc alloy is then precipitated electrolytically on the sintered material thus produced and, finally, the zinc is dissolved out by dipping in lye. The carrier may be of metal and particularly a wire lattice of nickel or iron. It may also be a solid electrolyte membrane, such as a disc of .beta.-Al.sub.2 O.sub.3.

Method of making a porous nickel electrode for alkaline electrolysis

A method for producing hydrogen according to a hybrid process. A low oxide, hich is formed at a high temperature from a higher oxide accompanied by splitting-off of oxygen, is introduced into an aqueous electrolyte and is reoxidized anodically along with simulataneous cathodic hydrogen generation. The oxide is returned into the high temperature range. As an oxide, antimony oxide, especially antimony tetraoxide, is used, with the oxide being formed anodically in a melt-flow electrolysis and being decomposed again into antimony trioxide and oxygen at approximately 850.degree. to 1000.degree. C. As an electrolyte, an alkali melt, and especially a melt having a sodium hydroxide base, may be used. The electrolyte may be formed by a possibly salt, especially sodium fluoride, containing mixture of sodium hydroxide and antimony trioxide in a mole ratio of 1:0.5 to 1:5.0, with a water content of approxaimately 1 to 5% by weight. The anode chamber is separated from the cathode chamber by a .beta.-aluminum oxide separating wall.

Hybrid process for producing hydrogen

Method and apparatus for generating hydrogen and oxygen. Water is electroically decomposed in an electrolysis cell having a molten electrolyte which contains alkali ions and has a high OH.sup.- ion activity. The anode and cathode chambers are separated from one another by a separator made of an ion conducting aluminum oxide modification known as .beta.-Al.sub.2 O.sub.3. Hydrogen and oxygen are then separately withdrawn.

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Julich, Germany

Jiri Divisek