Anode for oxygen generation and manufacturing method for the same

Abstract

The present invention aims to provide an anode for oxygen generation and a manufacturing method for the same used for industrial electrolyses including manufacturing of electrolytic metal foils such as electrolytic copper foil, aluminum liquid contact and continuously electrogalvanized steel plate, and metal extraction. The present invention features an anode for oxygen generation and a manufacturing method for the same comprising a conductive metal substrate and a catalyst layer containing iridium oxide formed on the conductive metal substrate wherein the coating is baked in a low temperature region of 370° C.-400° C. in an oxidation atmosphere to form the catalyst layer containing amorphous iridium oxide and the catalyst layer containing amorphous iridium oxide is post-baked in a further high temperature region of 520° C.-600° C. in an oxidation atmosphere to crystallize almost all amount of iridium oxide in the catalyst layer.

Description

TECHNICAL FIELD[0001]The present invention relates to an anode for oxygen generation used for various industrial electrolyses and a manufacturing method for the same; more in detail, it relates to a high-load durable anode for oxygen generation and a manufacturing method for the same used for industrial electrolyses including manufacturing of electrolytic metal foils such as electrolytic copper foil, aluminum liquid contact, and continuously electrogalvanized steel plate, and metal extraction.BACKGROUND ART[0002]Mixing of lead ions in the electrolytic cell is often seen in various types of industrial electrolysis. Mixing of lead compounds in the production of electrolytic copper foil as its typical example is derived from the following two points: that is, sticking to, as a lead alloy, a scrap copper which is one of the raw materials of copper sulfate in electrolyte, and before DSE (registered trademark of Permelec Electrode Ltd.) type of electrode being used, lead-antimony electrod...

AI Technical Summary

Benefits of technology

The present invention relates to a method for forming an electrode catalyst layer containing iridium oxide. The method involves baking in two stages: a low temperature region of 370°C-400°C in an oxidation atmosphere to form a catalyst layer containing amorphous iridium oxide, followed by a high temperature region of 520°C-600°C in an oxidation atmosphere to crystallize most of the iridium oxide and suppress the growth of crystallite diameter. This results in an electrode effective surface area of the catalyst layer increased and a decrease in oxygen generation overvoltage, promoting oxygen generation and suppressing the reaction to form PbO2 from lead ion. The method also improves durability of the electrode by dispersing current distribution and reducing wear rate of the catalyst layer by electrolysis.

Problems solved by technology

However, an influence by floating fine particles such as lead ion, Pb2+, or lead compounds, PbSO4 against an electrode for electrolysis and an electrolytic copper foil which is an electrolytic product cannot be made light of.

Since oxidized lead-β-PbO2 has a small electrode catalyst function, a total surface of an electrode is covered by it, although an electrode potential increases, an electrolysis continuously occurs and an electrode life as a coating to protect the electrode is prolonged, but if it is partially peeled off, an original electrode catalyst layer of which catalyst activity is high, is exposed, and therefore an electrolysis current of it increases and an unevenness of a foil thickness of copper foil growing on an opposite cathode drum is caused.

SHE) (exactly 1.632−0.0886 pH−0.0295p(HSO4−)) and so a problem that electrolysis voltage rises after electrolysis appears.

Also the following problem occurs: Fine particles of PbSO4 floating in the electrolyte adhere to the surface of the electrolytic copper foil and are embroiled in a roll of electrolytic copper foil.

However, after a lead-free solder penetrated, there is time lag up to replace to scrap copper of the lead-free and in the point of cost, it is predicted that the coexistence with the lead ion continues for a while now.

Furthermore, as an electrode for this kind of electrolysis, together with reducing the influence of the lead ion as much as possible, electrode with a low oxygen generation potential and a long service life is required.

Since the electrode is baked at a temperature of 650° C. or more, the metal substrate, such as of titanium causes interfacial corrosion, and becomes poor conductor, causing oxygen overvoltage to increase to an unserviceable degree as electrode.

Moreover, the crystallite diameter of iridium oxide in the catalyst layer enlarges, resulting in decreased an electrode effective surface area of the catalyst layer, leading to a poor catalytic activity.

This electrode, however, features amorphous iridium oxide, and is insufficient in electrode durability.

The electrode disclosed by PTL 3 is insufficient in electrode durability because the upper layer of the catalyst layer is amorphous iridium oxide.

Moreover, crystalline iridium oxide exists only in the lower layer, not uniformly distributed over the entire catalyst layer, resulting in insufficient electrode durability.

However, it is thought that electrode durability of these two electrodes is not enough because they contain a large amount of amorphous iridium oxide, as a prerequisite.

Images