Method for electrolyzing alkaline water

Patent metadata

Field	Value
Publication number	US-2018334751-A1
Application number	US-201615775267-A
Country	US
Kind code	A1
Filing date	Dec 22, 2016
Priority date	Dec 28, 2015
Publication date	Nov 22, 2018
Grant date	—

Abstract

Provided is an alkaline water electrolysis method capable of reducing or preventing degradation in cathode and anode performance even in an operation of repeated cycles of frequent starting and stopping, and/or even in an operation involving a significant output variation.
The present invention provides an alkaline water electrolysis method including repeated cycles of intermittent operation, including an electrolysis step of performing alkaline water electrolysis including storing an electrolytic solution ( 16 ) in a circulation tank ( 5 ), feeding the electrolytic solution ( 16 ) in the circulation tank ( 5 ) to an anode chamber ( 2 ) and to a cathode chamber ( 3 ), returning an electrolytic solution generated in the cathode chamber ( 3 ) and an electrolytic solution generated in the anode chamber ( 2 ) to the circulation tank ( 5 ), mixing together these electrolytic solutions in the circulation tank ( 5 ), and recirculating the mixed electrolytic solution to the anode chamber ( 2 ) and to the cathode chamber ( 3 ), and a step of adding a catalyst activation material formed of a metal salt soluble in the electrolytic solution ( 16 ) prior to starting of the electrolysis step; and in the electrolysis step, a metal component in the catalyst activation material is deposited on a surface of the cathode.

First claim

1 . An alkaline water electrolysis method for electrolyzing an alkaline electrolytic solution using an alkaline water electrolyzer having an anode chamber housing an anode, a cathode chamber housing a cathode, and a diaphragm separating the anode chamber from the cathode chamber, the method comprising:
an electrolysis step of performing alkaline water electrolysis in the alkaline water electrolyzer, including storing the electrolytic solution in a circulation tank, feeding the electrolytic solution stored in the circulation tank to the anode chamber and to the cathode chamber, returning a cathode-side electrolytic solution generated in the cathode chamber and an anode-side electrolytic solution generated in the anode chamber to the circulation tank, mixing together the cathode-side electrolytic solution and the anode-side electrolytic solution in the circulation tank, and circulating the mixed electrolytic solution between the cathode chamber and the circulation tank and between the anode chamber and the circulation tank; and a step of adding a catalyst activation material formed of a metal salt soluble in the electrolytic solution prior to starting of the electrolysis step, wherein in the electrolysis step, a metal component in the catalyst activation material is deposited on a surface of the cathode.

2 . The alkaline water electrolysis method according to claim 1 , wherein during a period in which the electrolysis step is not performed, a reverse current flows to cause a metal component in the catalyst activation material to be deposited on a surface of the anode.

3 . The alkaline water electrolysis method according to claim 1 , wherein after starting of the electrolysis step, the catalyst activation material is further added to the electrolytic solution during the electrolysis step.

4 . The alkaline water electrolysis method according to claim 1 , wherein, in the electrolysis step, pure water is added to the electrolytic solution to maintain an alkali concentration of the electrolytic solution at a predetermined concentration.

5 . The alkaline water electrolysis method according to claim 1 , wherein the catalyst activation material is a compound of at least one metal selected from the group consisting of ruthenium, palladium, iridium, platinum, nickel, and cobalt.

6 . The alkaline water electrolysis method according to claim 1 , wherein the catalyst activation material is deposited on the surface of the cathode in an amount ranging from 0.1 to 15 g/m 2 in terms of the metal component.

7 . The alkaline water electrolysis method according to claim 2 , wherein the catalyst activation material is deposited on the surface of the anode in an amount ranging from 0.1 to 15 g/m 2 in terms of the metal component.

8 . The alkaline water electrolysis method according to claim 1 , wherein the anode has a structure in which an anode catalyst material formed of at least one selected from the group consisting of Raney nickel, nickel oxide, nickel cobalt oxide, cobalt oxide, lanthanum-doped cobalt oxide, lanthanum strontium cobalt oxide, zinc cobalt oxide, ruthenium oxide, rhodium oxide, palladium oxide, osmium oxide, iridium oxide, and platinum is coated on a surface of an electrically conductive base member.

9 . The alkaline water electrolysis method according to claim 1 , wherein the cathode has a structure in a cathode catalyst material formed of at least one selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium, platinum, and Raney nickel is coated on a surface of an electrically conductive base member.

10 . The alkaline water electrolysis method according to claim 8 , wherein the conductive base member is made of at least one selected from the group consisting of nickel, a nickel-based alloy, iron, an iron-based alloy, and a carbon material.

Assignees

• De Nora Permelec Ltd

Inventors

• Manabe Akiyoshi

Classifications

• C25B15/08 Primary

  Supplying or removing reactants or electrolytes; Regeneration of electrolytes · CPC title

• Y02P20/133

  Renewable energy sources, e.g. sunlight · CPC title

• C25B11/0473

  Chemistry & Metallurgy · mapped topic

• C25B11/0415

  Chemistry & Metallurgy · mapped topic

• C25B11/0405

  Chemistry & Metallurgy · mapped topic