Method For Improving The Performance of Nickel Electrodes

1 . A method for improving the performance of nickel electrodes that are used in a membrane sodium chloride electrolytic process comprising:

(a) preparing a water-soluble or alkali-soluble platinum solution comprising:

(i) a solvent and

(ii) a soluble platinum compound

and

(b) adding the solution to the catolyte

and thereby forming a coating on the nickel electrode.

2 . The method according to claim 1 , wherein the platinum compound is a water-soluble salt or a complex acid.

3 . The method according to claim 1 , wherein the platinum solution is hexachloroplatinic acid, or an alkali platinate, or a mixture thereof.

4 . The method according to claim 1 , wherein the soluble platinum compound is Na 2 PtCl 6 , or Na 2 Pt(OH) 6 , or a mixture thereof.

5 . The method according to claim 1 , wherein, after the addition of the platinum solution, the electrolytic voltage is varied in the range from 0V to 5V.

6 . The method according to claim 4 , wherein, after the addition of the platinum solution, the electrolytic voltage is varied in the range from 0V to 5V.

7 . The method according to claim 5 , wherein, after the addition of the platinum solution, the difference in the electrolytic voltage is from 0.5 to 500 mV.

8 . The method according to claim 6 , wherein, after the addition of the platinum solution, the difference in the electrolytic voltage is from 0.5 to 500 mV.

9 . The method according to claim 5 , wherein the voltage is varied by pulsing the voltage or by superimposing an alternating voltage on the electrolytic voltage, in the range from 0 to 5 V, and by a difference of from 0.5 to 500 mV.

10 . The method according to claim 8 , wherein the voltage is varied by pulsing the voltage or by superimposing an alternating voltage on the electrolytic voltage, in the range from 0 to 5 V, and by a difference of from 0.5 to 500 mV.

11 . The method according to claim 10 , which further comprises at least one additional water-soluble compound from Group VIII of the Periodic Table are added to the platinum solution.

12 . The method according to claim 1 , which further comprises at least one additional water-soluble compound from selected from the group consisting of palladium, iridium, platinum, rhodium, osmium and ruthenium.

13 . The method according to claim 11 , wherein, the additional water-soluble compound, based on the amount of platinum in the platinum compound, are present in a concentration of 1 wt. % to 50 wt. %.

14 . The method according to claim 12 , wherein, the additional water-soluble compound, based on the amount of platinum in the platinum compound, are present in a concentration of 1 wt. % to 50 wt. %.

15 . The method according to claim 1 , wherein the water soluble or alkali soluble platinum compound solution is metered at a rate of 0.001 g Pt/(h*m 2 ) to 1 g Pt/(h*m 2 ).

16 . The method according to claim 14 , wherein the water soluble or alkali soluble platinum compound solution is metered at a rate of 0.001 g Pt/(h*m 2 ) to 1 g Pt/(h*m 2 ).

17 . The method according to claim 15 , wherein the temperature at which the metering of the platinum solution is from 70° C. to 90° C.

18 . The method according to claim 16 , wherein the temperature at which the metering of the platinum solution is from 70° C. to 90° C.

19 . The method according to claim 15 , wherein the metering of the platinum solution occurs during electrolysis and under a current density between 0.1 to 10 kA/m 2 .

20 . The method according to claim 18 , wherein the metering of the platinum solution occurs during electrolysis and under a current density between 0.1 to 10 kA/m 2 .