Electrocatalyst, electrode coating and electrode for the preparation of chlorine

Patent metadata

Field	Value
Publication number	US-9677183-B2
Application number	US-201414174037-A
Country	US
Kind code	B2
Filing date	Feb 6, 2014
Priority date	Feb 8, 2013
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

Electrocatalyst, electrode coating and an electrode for preparing chlorine and process for producing the electrode, the electrocatalyst comprising a noble metal oxide and/or a noble metal of transition groups VIIIa of the Periodic Table of the Elements and at least one finely divided pulverulent oxide of another metal, in which one or more components are doped and the base metal oxide powder is chemically stable in the presence of aqueous electrolytes.

First claim

The invention claimed is:

1. Electrocatalyst for preparing chlorine by electrolysis of electrolytes containing chloride ions, comprising at least one noble metal oxide and/or noble metal of transition group VIIIa of the Periodic Table of the Elements wherein the catalyst further comprises at least one base metal oxide powder, wherein the base metal oxide powder is chemically stable in the presence of aqueous electrolytes, wherein the based metal oxide powder further comprises an electrically conductive matrix composed of noble metal oxide and/or noble metal, valve metal oxide and/or valve metal and/or doped base metal oxide in which the finely divided, optionally doped, base metal oxide powder is embedded, and wherein the average particle diameter of the particles of base metal oxide powder is not more than 1 μm.

2. Electrocatalyst according to claim 1 , wherein said noble metal or noble metal oxide is one or more members of the group consisting of ruthenium, iridium, platinum, palladium and oxides thereof.

3. Electrocatalyst according to claim 2 , wherein the noble metal or noble metal oxide is one or more of ruthenium and iridium or ruthenium oxide and iridium oxide.

4. Electrocatalyst according to claim 1 , wherein the base metal oxide of the base metal oxide powder comprises one or more oxides and/or mixed oxides selected from the group consisting of titanium oxide, tin oxide, niobium oxide, tantalum oxide, vanadium oxide, germanium oxide, tellurium oxide, lead oxide, manganese oxide, iron-antimony oxide and molybdenum oxide.

5. Electrocatalyst according to claim 1 , wherein the base metal oxide of the base metal oxide powder comprises titanium oxide, tin oxide or both.

6. Electrocatalyst according to claim 1 , wherein the catalyst further comprises a further doped base metal oxide selected from the group consisting of antimony-doped tin oxide (ATO), indium-tin oxide (ITO), fluorine-doped tin oxide (FTO), aluminium-doped zinc oxide (AZO), and indium-doped zinc oxide (IZO).

7. Electrocatalyst according to claim 1 , wherein the base metal oxide powder comprises both particles having approximately spherical symmetry and fibrous particles.

8. Electrocatalyst according to claim 7 , wherein the base metal oxide powder comprises fibrous particles having an average length of up to 100 μm.

9. Electrocatalyst according to claim 1 , wherein the specific surface area of the base metal oxide powder is from 0.5 m 2 /g to 500 m 2 /g.

10. Electrocatalyst according to claim 1 , wherein the base metal oxide of the base metal oxide powder is doped with one or more doping elements selected from the group consisting of antimony, niobium, tantalum, iridium and fluorine, the proportion of which is from 0.0001 to 0.1 mol of doping element per mol of total other metals present in the base metal oxide.

11. Electrocatalyst according to claim 1 , wherein the catalyst comprises from 1 to 90 mol % of finely divided base metal oxide powder and from 0.05 to 40 mol % of noble metal and/or noble metal oxide and from 0 to 90 mol % of valve metal and/or valve metal oxide, and from 0 to 90 mol % of a doped base metal oxide.

12. Electrocatalyst according to claim 1 , wherein the catalyst comprises from 20 to 70 mol % of finely divided base metal oxide, from 5 to 30 mol % of noble metal and/or noble metal oxide and from 10 to 75 mol % of valve metal and/or valve metal oxide and from 0.1 to 20 mol % of a doped base metal oxide.

13. Electrocatalytic coating comprising at least one electrocatalyst according to claim 1 .

14. Electrode for preparing chlorine by electrolysis of aqueous electrolytes containing chloride ions, which is formed of at least an electrically conductive support and a catalytically active coating, wherein the catalytically active coating contains an electrocatalyst of claim 1 .

15. Electrode according to claim 14 , wherein the electrically conductive support is formed of a valve metal selected from the group consisting of titanium, zirconium, tungsten, tantalum and niobium.

16. Electrode according to claim 14 wherein the loading of the electrode is from 0.1 to 30 g of noble metal/m 2 and from 0.1 to 75 g of finely divided base metal oxide/m 2 .

17. Process for producing the electrode of claim 14 , wherein a layer of at least one finely divided base metal oxide power and at least one noble metal oxide and/or noble metal of transition group VIIIa of the Periodic Table of the Elements and optionally also of at least one valve metal or a valve metal oxide or mixtures thereof and optionally also a doped base metal oxide powder is applied to an electrically conductive support formed of a valve metal selected from the group consisting of titanium, zirconium, tungsten, tantalum and niobium, by applying a mixture of base metal oxide powder, a solvent and a noble metal compound and a soluble base metal compound and optionally a soluble valve metal compound and/or optionally a soluble doping element compound to the electrically conductive support and drying to remove solvent and subsequently sintering at elevated temperature.

18. Electrode produced by the process of claim 17 .

19. Method for the electrochemical preparation of chlorine from hydrogen chloride solutions or alkali metal chloride solutions, or for generating electric current, in the electrolysis of water, the regeneration of chromium baths, or in the use of fluoride-containing electrolytes in hydrogen peroxide, ozone or peroxodisulphate production with the electrode of claim 14 .

20. Electrode according to claim 14 wherein the average particle diameter of the particles of the base metal oxide powder is from 5 to 800 nm.

Assignees

• Covestro Deutschland Ag
• Nano-X-Gmbh

Inventors

• Kintrup Juergen
• Bulan Andreas
• Hammarberg Elin
• Sepeur Stefan
• Frenzer Gerald
• Gross Frank
• Eiden Stefanie

Classifications

• C25B11/063

  Valve metal, e.g. titanium · CPC title

• C25B1/26

  Chlorine; Compounds thereof (by simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine C25B1/34) · CPC title

• B01J23/468

  Iridium · CPC title

• B01J23/462

  Ruthenium · CPC title

• C25B11/0484 Primary

  Chemistry & Metallurgy · mapped topic