Hoechst Aktiengesellschaft

Rudolf Staab

Kurt Hannesen

August Winsel

Dieter Bergner

Jurgen Russow

Nikolaj Medic

A process is described for electrolyzing aqueous alkali metal chloride solutions in a membrane cell which contains an anode chamber with the anode and a cathode chamber with the cathode, the two chambers being separated from one another by a cation exchanger membrane. The cathode is porous and foil-like. The cathode and cation exchanger membrane form the actual cathode chamber filled with catholyte and the cathode and cell wall form a gas space. Water is fed into the cathode chamber and alkali metal hydroxide solution is withdrawn from it, hydrogen is withdrawn from the cathode chamber and gas space, and aqueous alkali metal chloride solution is fed into the anode chamber and gaseous chlorine, together with depleted alkali metal chloride solution, is withdrawn from it. A direct voltage which is at least the same as the decomposition voltage is applied to the cathode and anode. A higher pressure is established in the cathode chamber than in the gas space.

Process for the electrolysis of alkali metal chloride solutions

In this electrolysis apparatus for the preparation of chlorine from aqueous alkali halide solutions, which comprises at least one electrolytic cell, the anode and gas diffusion cathode are disposed horizontally and separated from each other by a partition in a housing consisting of two half shells and are connected mechanically and in an electrically conducting manner by means of their edges to the respective half shells. In addition, the cathode is connected in a liquid-tight manner to its half shell and is supported by a current supply and distribution device. The partition is clamped between a circumferential seal between the edges of the half shell and a frame and is supported on a spacer which rests on the cathode and is held by the frame. The frame contains an inlet and outlet for the catholyte.

Electrolysis apparatus with horizontally disposed electrodes

A gas-diffusion cathode is to be used in the trough-like electrolysis cell with horizontally disposed electrodes which are separated from each other by a membrane. The gas-diffusion cathode (3) rests on a grating (4) with supporting legs (2). A spacer (8) is disposed between membrane (6) and gas-diffusion cathode (3).

Electrolysis cell with horizontally disposed electrodes

Metallic silver is deposited from a silver salt solution onto a support by reduction, and thus a catalytically active electrode material for oxygen-consuming electrodes is obtained. For this purpose,

Process for the preparation of a catalytically active electrode material

In this electrolysis apparatus, the anode and the gas diffusion cathode are arranged to be separated from one another by means of a partition. At least one element (6) which has the form of a twin trough is located between two half-shells (1, 2) which are located at the ends and of which one carries an anode (4) and the second carries a cathode (5). This twin trough is formed by a common plate (7) and a lateral wall (8), the height of which is divided by the plate and the edges of which are provided with flanges (9, 10). The anode (4) and the cathode (5) are electrically conductively connected to the wall (8) and to struts (13) which protrude vertically from the plate on both sides. In order to form a cavity (16) between the partition (14) and the cathode (5), a sealing element is arranged between these two.

Bipolar electrolysis apparatus with gas diffusion cathode

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.

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Kelkheim, Germany

Rudolf Staab