Titanium Anode Catalyst Layers for Iridium-Free Chlorine Electrolysis
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Solution Overview
Problem
The high cost and scarcity of iridium, a noble metal used in chlorine evolution electrolysis, necessitate the development of an anode with superior chlorine evolution efficiency and low overvoltage without relying on iridium.
Innovation Solution
An anode composed of a titanium substrate with a laminated catalyst layer containing oxides of ruthenium, tin, and zirconium in the first layer, and ruthenium and titanium in the second layer, optimized in specific molar ratios, to achieve low overvoltage and high chlorine evolution efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an electrode employing noble metal oxide such as iridium oxide as a catalyst is used, then the overvoltage for chlorine evolution is low and chlorine evolution efficiency is superior, but the cost is high and iridium availability is low
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst layer by replacing iridium oxide with a combination of ruthenium oxide, tin oxide, and zirconium oxide in specific proportions. This parameter change maintains the catalytic activity for chlorine evolution while eliminating dependence on scarce iridium metal.
Solution Approach 2:
The patent employs a composite catalyst layer consisting of multiple metal oxides (ruthenium oxide, tin oxide, zirconium oxide) combined in specific ratios. This composite material approach achieves the catalytic performance previously attainable only with expensive noble metal oxides, thereby reducing iridium usage while maintaining high chlorine evolution efficiency.
2Productivity
If a catalyst coating containing oxides of tin, iridium, and ruthenium is used, then chlorine evolution efficiency is improved, but the cost increases due to iridium content
Solution Approach 1:
The patent extracts iridium from the catalyst coating composition and replaces it with a combination of ruthenium oxide, tin oxide, and zirconium oxide. This extraction of the expensive noble metal while maintaining catalytic functionality reduces manufacturing cost while preserving chlorine evolution efficiency.
Solution Approach 2:
The patent substitutes expensive iridium oxide with relatively cheaper metal oxide combinations (ruthenium, tin, zirconium oxides). Although these materials may have different stability characteristics, the cost advantage is significant, and the catalyst layer is designed to maintain adequate performance throughout its service life.
3Use of energy by moving object
If an electrode with high chlorine evolution efficiency is used, then the overvoltage is low, but iridium consumption is high
Solution Approach 1:
The patent optimizes the compositional parameters of the catalyst layer by specifying precise ranges for ruthenium oxide (10-40 wt%), tin oxide (50-85 wt%), and zirconium oxide (5-20 wt%). This parameter optimization achieves low overvoltage for chlorine evolution without requiring any iridium, thereby decoupling energy efficiency from noble metal consumption.
Solution Approach 2:
The patent creates a composite catalyst system where ruthenium oxide provides catalytic activity, tin oxide enhances stability and reduces overvoltage, and zirconium oxide improves structural integrity. This synergistic composite material achieves low overvoltage and high chlorine evolution efficiency without iridium content.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The anode achieves low overvoltage and high chlorine evolution efficiency without using iridium, utilizing readily available materials and maintaining stability over long-term electrolysis.
Implementation Method 1
on the anode, chloride ions (Cl -) are oxidized to evolve chlorine (Cl 2 )
Implementation Method 2
chlorine gas, a chlorine compound, and the like are produced by electrolysis of salt water
Implementation Method 3
An electrode employing a noble metal oxide such as iridium oxide (IrO 2 ) as a catalyst is used. An electrode employing such a noble metal oxide as a catalyst has a low overvoltage for chlorine evolution
Data Source
Figure 1~2
Figure 3
AI summary
Provided is an anode for chlorine evolution electrolysis having a low overvoltage for chlorine evolution and an excellent efficiency in chlorine evolution without using iridium (Ir). The anode is an anode 10 for chlorine evolution electrolysis, including: a substrate 2 formed of titanium or a titanium alloy; and a catalyst layer 5 having a first layer 5a disposed on the substrate 2 and a second layer 5b disposed on the first layer 5a, in which the first layer 5a contains respective oxides of ruthenium (Ru), tin (Sn), and zirconium (Zr), and the second layer 5b contains respective oxides of ruthenium (Ru) and titanium (Ti).