Process for the electrolysis of an aqueous solution of alkali metal chloride

• US 20030121795A1
• Filed: 12/03/2002
• Published: 07/03/2003
• Est. Priority Date: 12/05/2001
• Status: Active Grant

• Current Assignee: Bayer Materialscience AG (Covestro AG)
• Original Assignee: Bayer AG
• Inventors: Gestermann, Fritz, Pinter, Hans-Dieter, Bulan, Andreas
• Granted Patent: US 6,890,418 B2
• Time in Patent Office: Days
• US Class Current: 205/510
• CPC Class Codes: C25B 1/46 in diaphragm cells

Abstract

The invention describes a process for the electrolysis of an aqueous solution of alkali metal chloride, in particular sodium chloride, by the membrane process with an aqueous solution of alkali metal hydroxide, in particular sodium hydroxide, as catholyte, where the temperature of the alkali metal chloride solution in the anode half-element and/or the volume flow rate of the alkali metal chloride solution in the anode half-element are set in such a way that the difference between the temperature of the alkali metal hydroxide solution at the entry into the cathode half-element and the temperature of the alkali metal hydroxide solution at the exit from the cathode half-element are not greater than 15° C.

Claims

1. Process for the electrolysis of an aqueous solution of alkali metal chloride, in particular sodium chloride, by the membrane process with an aqueous solution of alkali metal hydroxide, in particular sodium hydroxide, as catholyte, characterized in that the temperature of the alkali metal chloride solution in the anode half-element and/or the volume flow rate of the alkali metal chloride solution in the anode half-element are set in such a way that the difference between the temperature of the alkali metal hydroxide solution at the entry into the cathode half-element and the temperature of the alkali metal hydroxide solution at the exit from the cathode half-element are not greater than 15°

C.

2. Process according to claim 1, characterized in that the temperature of the alkali metal chloride solution on exiting from the anode half-element and the temperature of the alkali metal hydroxide solution on exiting from the cathode half-element are from 80°

C. to 100°

C., preferably from 85°

C. to 95°

C.

3. Process according to one of claims 1 and 2, characterized in that the flow rate of the alkali metal hydroxide solution in the cathode half-element is less than 1 cm/s.

4. Process according to one of claims 1 to 3, characterized in that the cathode employed is a gas diffusion electrode.