Anode for electrolytic evolution of chlorine

Patent metadata

Field	Value
Publication number	US-2021238757-A1
Application number	US-201916973245-A
Country	US
Kind code	A1
Filing date	Jun 13, 2019
Priority date	Jun 21, 2018
Publication date	Aug 5, 2021
Grant date	—

Abstract

The invention relates to a process for obtaining a electrode usable as a anode in electrolytic cells for the production of chlorine. The electrode thus obtained comprises a catalytic layer containing oxides of tin, ruthenium, iridium and titanium applied to a substrate of a valve metal.

First claim

1 . An electrode for gas evolution in electrolytic processes comprising a valve metal substrate and a catalytic coating containing 5-40% of tin, 3.6-15% of iridium, 18-40% of ruthenium and 30-70% of titanium, in the form of metals or their oxides in molar percentage referred to the elements, said catalytic coating obtained by thermal decomposition of an acetic solution containing hydroxyacetochloride complexes of iridium, ruthenium, tin and titanium.

2 . The electrode according to claim 1 , wherein said catalytic coating contains 6-30% of tin, 3.7-12% of iridium, 20-30% of ruthenium and 50-70% of titanium, in the form of metals or their oxides in molar percentage referred to the elements.

3 . The electrode according to claim 1 , wherein said catalytic coating contains 8-18% of tin, 4-10% of iridium, 18-36% of ruthenium and 45-65% of titanium, in the form of metals or their oxides in molar percentage referred to the elements.

4 . The electrode according to claim 1 , wherein said catalytic coating has a specific load of noble metal expressed as the sum of iridium and ruthenium comprised between 6 and 12 g/m 2 .

5 . The electrode according to claim 1 , wherein said catalytic coating is obtained by thermal decomposition an acetic solution containing hydroxyacetochloride complexes of iridium, ruthenium, tin and titanium, said solution containing 5-40% of tin, 3.6-15% of iridium, 18-40% of ruthenium and 30-70% of titanium, in molar percentage referred to the elements.

6 . A method for the production of an electrode as defined in claim 1 , comprising the following steps:
a) applying to a valve metal substrate of an acetic solution containing hydroxyacetochloride complexes of iridium, ruthenium, tin and titanium, subsequent drying at 50-60° C. and thermal decomposition at 450-600° C. for a time of 5 to 30 minutes until reaching a specific noble metal loading expressed as the sum of iridium and ruthenium between 0.4 and 1 g/m 2 ; b) repeating step a) until obtaining a catalytic coating with a specific noble metal loading of 6 to 12 g/m 2 ; c) heat treating at 450-600° C. for a time of 50 to 200 minutes.

7 . The method according to claim 6 , wherein said acidic solution contains 5-40% of tin, 3.6-15% of iridium, 18-40% of ruthenium and 30-70% of titanium, preferably 6-30% of tin, 3.7-12% of iridium, 20-30% of ruthenium and 50-70% of titanium and more preferably 8-18% of tin, 4-10% of iridium, 18-36% of ruthenium and 45-65% of titanium, in molar percentage referred to the elements.

8 . A method for the production of an electrode for gas evolution in electrolytic processes comprising the following steps:
a) applying to a valve metal substrate of an acetic solution containing hydroxyacetochloride complexes of iridium, ruthenium, tin and titanium complexes containing 5-40% of tin, 3.6-15% of iridium, 18-40% of ruthenium and 30-70% of titanium, in molar percentage referred to the elements; subsequent drying at 50-60° C. and thermal decomposition at 450-600° C. for a time of 5 to 30 minutes until reaching a specific noble metal loading expressed as the sum of iridium and ruthenium of 0.4 to 1 g/m 2 ; b) repeating step a) until obtaining a catalytic coating with a specific noble metal loading of 6 to 12 g/m 2 ; c) heat treating at 450-600° C. for a time of 50 to 200 minutes.

9 . The method according to claim 8 , wherein said acidic solution contains 6-30% of tin, 3.7-12% of iridium, 20-30% of ruthenium and 50-70% of titanium and preferably 8-18% of tin, 4-10% of iridium, 18-36% of ruthenium and 45-65% of titanium, in molar percentage referred to the elements.

10 . The method according to claim 6 where the temperature of said thermal decomposition in steps a) and c) is between 480 and 550° C.

11 . A cell for the electrolysis of solutions of alkaline chlorides comprising an anodic compartment and a cathodic compartment where the anodic compartment is equipped with the electrode according to claim 1 .

12 . The cell for electrolysis according to claim 11 wherein said anodic compartment and said cathodic compartment are separated by a diaphragm or an ion-exchange membrane.

13 . An electroyzer for the production of chlorine and alkali from alkali chloride solutions comprising a modular arrangement of cells according to claim 12 .

Assignees

• Industrie De Nora Spa

Inventors

• Gargiulo Alice
• Calderara Alice
• Iacopetti Luciano

Classifications

• C23C18/1241

  Metallic substrates · CPC title

• C23C18/08

  characterised by the deposition of metallic material · CPC title

• C23C18/1295

  with after-treatment of the deposited inorganic material · CPC title

• C23C18/1216 Primary

  Metal oxides (C23C18/1212 takes precedence) · CPC title

• C23C18/1225

  Deposition of multilayers of inorganic material · CPC title