Hoechst Aktiengesellschaft

Other

Jurgen Russow

Hans-Peter Rieck

Karl-Heinz Tetzlaff

Dieter Schmid

Martin Schott

Dieter Bergner

Rudolf Staab

Theodor Auel

Hans-Joachim Semmler

Gerhard Munster

Nikolaj Medic

Gerhard Riess

Heinz Kau

A process for the manipulation of liquid electrolyte and gas during the operation of an electrochemical cell having at least one gas diffusion electrode and a counter electrode forming an electrolyte space for a flowing electrolyte which flows through the cell, from the upper end of the cell to its lower end, which electrolyte space is nonpartitioned or is partitioned by a separator, the gas diffusion electrode having a surface facing toward the electrolyte space and an opposite surface facing opposite from the electrolyte space, and the cell having a gas space located on the opposite surface, the process comprising:

Electrochemical process for treating liquid electrolytes

In this process for electrically separating the electrolyte-bearing main from the electrolyte spaces of an electrochemical cell pile, the electrolyte is passed via drop sections directly from the main into the electrolyte space or directly from the electrolyte space into the main.

Process for electrically separating the electrolyte-bearing mains from

Moldings are described which are composed of a silicic acid with a layer structure, or salts thereof with the general formula (H,M).sub.2 Si.sub.y O.sub.2y+1, or the corresponding hydrates, M representing lithium, sodium, potassium or ammonium and y being 1.7 to 24. They can be prepared for example by extruding pulverulent layer silicic acids, or salts thereof with the general formula (H,M).sub.2 Si.sub.y O.sub.2y+1, or the corresponding hydrates, M representing lithium, sodium, potassium or ammonium and y being 1.7 to 24, to produce cylindrical blanks, if appropriate after moistening with water or an organic solvent, and then drying the blanks, or by introducing the same starting materials into a mold, as dry or moist powders, converting them to moldings with the application of pressure and, if appropriate, drying the moldings.

Moldings made of silicate material and processes for their preparation

A process for the production of shaped articles from silicate material by extrusion and/or pelleting and subsequent annealing is described. In this process, pulverulent layered silicic acids of the general formula H.sub.2 Si.sub.y O.sub.2y+1, in which y is a number from 1.7 to 24, or salts thereof, in which all or some of the H is replaced by at least one cation from the group comprising Li.sup.+, Na.sup.+, K.sup.+, NH.sub.4.sup.+, Ca.sup.2+, Cu.sup.2+, Co.sup.2+, Ni.sup.2+ and Mg.sup.2+, are mixed with water or an organic solvent, the mixture is extruded and/or pelleted to give roll-shaped or tube-shaped pieces and these are then dried and annealed under conditions such that the starting material is chiefly converted into cristobalite and/or tridymite. The same material can also be pressed in a molding tool under pressure. Under these conditions, shaped articles which predominantly consist of cristobalite or tridymite and have a Shore hardness of at least 70 can be obtained.

Shaped articles of silicate material, a process for their production and

This process, in which gas bubbles are formed in the electrolyte, is carried out in electrolytic cells which are non-partitioned or partitioned by at least one separator and in which at least one electrode is perforated. For this purpose, the electrolyte is caused to flow by means of gravity through the electrolytic cell in such a manner that a gas space is formed laterally to the main direction of flow of the electrolyte, both electrodes or the separators or one separator and the perforated electrode being wetted.

Process for the electrolysis of liquid electrolytes using film flow

This process can be carried out in an electrolytic cell which is non-partitioned or partitioned by at least one separator and has at least one porous electrode. The electrolyte enters parallel to the surface of the electrode and is forced by at least one restriction point to flow through the porous electrode parallel to the flow of charge.

Electrolysis process using liquid electrolytes and porous electrodes

A process is described for increasing the sulfuric acid concentration of solutions containing an alkali metal sulfate, sulfuric acid and alkaline earth metal ions. The solutions to be worked up are introduced into the anode compartment of an electrolysis cell. The anode compartment and the cathode compartment of the cell are each bounded by a cation exchange membrane. A center chamber is located between the two membranes. This center chamber is filled with an aqueous solution containing alkali metal ions. The concentration of alkaline earth metal ions in the solution in the center chamber must be kept below 5 mg/l during the electrolysis.

Process for the concentration of sulfuric acid

A gas diffusion electrode for the reduction of oxygen, which contains a hydrophobic electro-catalyst layer, is described. One side of this layer is covered with a hydrophilic layer which is composed of at least one transition metal or an oxide or mixed oxide of transition metals and can also contain a current collector in the form of a mesh. For producing the gas diffusion electrode, a hydrophobic electro-catalyst layer can first be prepared from a pulverulent mixture which contains the electro-catalyst and a hydrophobic polymer, and at least one transition metal or an oxide or mixed oxide of transition metals can be applied in a finely divided form to one side of this layer and bonded to the hydrophobic electro-catalyst layer by the application of pressure.

Gas diffusion electrode with a hydrophilic covering layer, and process

Ammonium nitrilotrisulfonate is obtained by introducing nitric oxides into an aqueous ammonium sulfite solution at a pH of 5.0-7.5. The solution should contain at least 20 g/l of ammonium nitrilotrisulfonate in suspended form.

Process for the manufacture of ammonium nitrilotrisulfonate

The invention relates to a process for the preparation of highly pure phosphorus pentachloride in the form of a free-flowing crystalline powder by reaction of phosphorus trichloride with chlorine. The reaction is carried out in two stages. In the first stage, phosphorus trichloride is combined with 0.1 to 0.999 times the molar amount of chlorine at a temperature of 0.degree. to 150.degree. C., while stirring, and is thereby reacted to give a crystal sludge comprising phosphorus pentachloride and phosphorus trichloride. In the second stage, this sludge is allowed to react with an excess of chlorine at 0.degree. to 150.degree. C. to give phosphorus pentachloride.

Process for the preparation of phosphorus pentachloride

Phosphorus pentachloride is manufactured from chlorine and phosphorus trichloride in the presence of molten phosphorus pentachloride. The process can be carried out such that the reaction product flows out from the reactor continuously as a melt. Reaction pressures of more than 1 bar and temperatures of from 160.degree. to 250.degree. C. are preferred.

Process for the manufacture of phosphorus pentachloride

For the electrolysis of an aqueous alkali metal chloride solution in a membrane cell with a perfluorinated cation exchange membrane it is important that there is only a minimum amount of cations of polyvalent metals, such as calcium. Otherwise, deposits within the membrane will occur, among other effects. It has been found that the disturbances caused by the above-mentioned cations can be considerably reduced, if an aliphatic polybasic phosphonic acid or the alkali metal salt thereof is added to the alkali metal chloride solution.

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Kelkheim, Germany

Jurgen Russow