Anode for electrolytic evolution of chlorine

Patent metadata

Field	Value
Publication number	US-2017306512-A1
Application number	US-201515521396-A
Country	US
Kind code	A1
Filing date	Nov 23, 2015
Priority date	Nov 24, 2014
Publication date	Oct 26, 2017
Grant date	—

Abstract

An electrode suitable as chlorine-evolving anode in electrolytic cells and a method for obtaining thereof is provided. The electrode has a metal substrate coated with a catalytic composition made of thin layers based on oxides of tin, iridium and ruthenium and combines excellent characteristics of anodic potential and selectivity with respect to the reaction of chlorine evolution without resorting to the use of dopants such as platinum and palladium.

First claim

1 . An electrode for evolution of gaseous products in electrolytic cells consisting of a metal substrate provided with a catalytic coating, said catalytic coating consisting of a mixture of oxides containing 55-70% by weight of tin, 5-20% by weight of iridium and 20-40% by weight of ruthenium referred to the metals, said catalytic coating being made up of layers with an average thickness of 0.1 to 0.4 μm, said catalytic coating having a total noble metal loading expressed as the sum of iridium and ruthenium referred to the metals of 2 to 25 g/m 2 .

2 . The electrode according to claim 1 , wherein said layers have a noble metal loading expressed as the sum of iridium and ruthenium referred to the metals of 0.2 to 1.4 g/m 2 per layer.

3 . The electrode according to claim 1 , wherein the total noble metal loading of said catalytic coating expressed as the sum of iridium and ruthenium referred to the metals is 5 to 12 g/m 2 .

4 . The electrode according to claim 1 wherein the ratio Ir/Ru is 0.3 to 0.4 by weight referred to the metals.

5 . The electrode according to claim 1 wherein said catalytic coating consists of a mixture of oxides containing 55-65% by weight of tin, 16-20% by weight of iridium and 20-25% by weight of ruthenium referred to the metals.

6 . A method for manufacturing an electrode according to claim 1 comprising the execution of the following sequential steps on a metal substrate:
a) applying a solution containing precursors of the components of said catalytic coating to the metal substrate with subsequent drying at 50-60° C. and thermal decomposition at 450-600° C. until reaching a specific noble metal loading of 0.2 to 1.4 g/m 2 ;
b) repeating step a) until obtaining a catalytic coating with a specific noble metal loading of 2 to 25 g/m 2 ; and
c) finally heat treating at 500-550° C. for a time of 50 to 200 minutes.

7 . The method according to claim 6 comprising an intermediate heat treatment at 500-550° C. for a time of 50 to 200 minutes carried out upon reaching the application of half the total loading of noble metal.

8 . An electrolysis cell of alkali chloride solutions comprising an electrode according to claim 1 as chlorine-evolving anode.

Assignees

• Industrie De Nora Spa

Inventors

• Gargiulo Alice
• Calderara Alice
• Pezzoni Chiara

Classifications

• C02F2001/46142

  Catalytic coating · CPC title

• C02F1/461

  by electrolysis · CPC title

• C02F1/46109

  Electrodes · CPC title

• C02F2101/12

  Halogens or halogen-containing compounds · CPC title

• C25B1/26 Primary

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