Method of operating an oxygen-consuming electrode

1. A method of operating an oxygen-consuming electrode as cathode for the electrolysis of alkali metal chlorides or hydrochloric acid, in an electrochemical cell, comprising feeding an oxygen-containing process gas to the electrode, wherein the oxygen-containing process gas is at least partly heated using a heat source from the electrolysis or from a work up process stream subsequent to the electrolysis before contact with the oxygen-consuming electrode to a temperature which corresponds to not more than the temperature of the cathode space in the cell or is less than 50° C. below the temperature of the cathode space in the cell;

wherein the heat source has a temperature of <150°.

2. The method according to claim 1 , wherein the oxygen-containing process gas is at least partly heated by heat exchange with a selected process stream obtained from the electrolysis or by heat exchange with a worked-up process stream subsequent to the electrolysis.

3. The method according to claim 1 , wherein the oxygen-consuming electrode is at least partly heated to a temperature which corresponds to not more than the temperature of the cathode space in the cell or is less than 20° C. below the temperature of the cathode space in the cell.

4. The method according to claim 1 , wherein the oxygen-consuming electrode is at least partly heated to a temperature which corresponds to not more than the temperature of the cathode space in the cell or is less than 10° C. below the temperature of the cathode space in the cell.

5. The method according to claim 1 , wherein chlorine gas taken off from the anode side of the electrochemical cell is utilized as a process stream for heat exchange for heating the oxygen-containing process gas.

6. The method according to claim 1 , wherein catholyte and/or anolyte leaving the cell is utilized as a process stream for heat exchange for heating the oxygen-containing process gas.

7. The method according to claim 1 , wherein cooling water, condensates or secondary steam from an alkali metal hydroxide solution evaporation plant downstream of the electrolysis cell is utilized as a process stream for the heat exchange for heating the oxygen-containing process gas.

8. The method according to claim 1 , wherein the oxygen-containing process gas is at least partly heated by passing the oxygen-containing process gas through an alkali metal hydroxide solution discharged from a catholyte circuit.

9. The method according to claim 1 , wherein condensed vapour from an alkali metal hydroxide solution evaporation downstream of the electrochemical cell is used as a process stream for heating the oxygen-containing process gas, wherein the oxygen-containing process gas is heated by passing the oxygen-containing process gas through the condensed vapour.

10. The method according to claim 1 , wherein the oxygen-containing process gas fed to the electrode has a proportion of from 30 to 95% by volume of oxygen.

11. The method according to claim 1 , wherein the oxygen-containing process gas fed to the electrode has a proportion of from 90 to 99% by volume of oxygen.

12. The method according to claim 1 , wherein the oxygen-containing process gas fed to the electrode has a proportion of greater than 99% by volume of oxygen.

13. The method according to claim 1 , wherein the oxygen-containing process gas fed to the electrode has a CO 2 content of <100 ppm.

14. The method according to claim 1 , wherein the electrolysis is a chloralkali electrolysis.

15. The method according to claim 1 , wherein the electrolysis is a sodium chloride electrolysis.

16. The method according to claim 1 , wherein the electrolysis is a hydrochloric acid electrolysis.