Chlorine-Evolution Electrode Coating with Lower Noble-Metal Loading
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Solution Overview
Problem
Existing catalytic coatings for electrolytic gas evolution in chlor-alkali electrolysis processes contain high noble metal loads, leading to high costs and performance issues due to contamination from excessive oxygen evolution, and are difficult to apply industrially due to volatile precursors.
Innovation Solution
A catalytic coating formulation comprising 10-20% tin, 25-45% ruthenium, 20-40% titanium, and 10-20% of niobium, tantalum, or tungsten, applied to a metal substrate, is prepared through thermal decomposition of their precursors, ensuring uniform distribution and reduced noble metal usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high quantities of noble metals (RuO2, IrO2, Pt) are used in catalytic coatings, then catalytic activity for chlorine evolution is improved, but cost increases and oxygen evolution contamination worsens
Solution Approach 1:
The patent changes the chemical composition parameters of the catalytic coating by replacing traditional noble metal formulations (RuO2 + IrO2/Pt) with a new formulation based on RuO2 mixed with SnO2 and TiO2. This parameter change maintains catalytic activity while reducing noble metal content and oxygen evolution contamination
Solution Approach 2:
The patent creates a composite catalytic coating material combining RuO2 with SnO2 and TiO2 in specific proportions (20-40 wt% SnO2, 10-30 wt% TiO2, balance RuO2). This composite formulation achieves the desired balance between catalytic activity, oxygen evolution suppression, and reduced noble metal loading
2Object-generated harmful factors
If SnO2 and TiO2 are added to RuO2 formulations to reduce oxygen evolution, then oxygen contamination is reduced, but catalytic activity for chlorine evolution decreases
Solution Approach 1:
The patent optimizes the weight percentage parameters of SnO2 (20-40%) and TiO2 (10-30%) in the formulation to achieve the optimal balance between suppressing oxygen evolution and maintaining chlorine evolution catalytic activity. This precise parameter control resolves the contradiction between reducing harmful oxygen evolution and preserving desired catalytic function
3Ease of manufacture
If tetravalent tin precursors (SnCl4) are used in coating preparation, then coating formulation is achieved, but volatility increases making industrial application difficult
Solution Approach 1:
The patent changes the physical state parameter of the tin precursor from gaseous SnCl4 to solid tin oxide (SnO2) powder. This parameter change eliminates the volatility problem while maintaining the ability to form the desired catalytic coating when mixed with RuO2 and TiO2
Solution Approach 2:
The patent replaces expensive and volatile SnCl4 with cheaper, non-volatile SnO2 powder. This substitution makes the coating preparation more suitable for industrial applications by eliminating handling difficulties associated with volatile precursors while maintaining the functional benefits of tin oxide in the catalytic coating
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 new coating achieves high catalytic activity for chlorine evolution with lower noble metal content, maintaining durability and reducing oxygen contamination, suitable for industrial applications.
Implementation Method 1
a catalytic coating containing oxides of tin, ruthenium, titanium and one or more elements selected from the group consisting of niobium, tantalum and tungsten
Implementation Method 2
the electrolysis process dates back to the late 19th century; and nowadays, the chlor-alkali industry is one of the main electrochemical processes for the production of chlorine and sodium hydroxide
Data Source
AI summary
An electrode for gas evolution in electrolytic processes comprising a catalytic coating containing oxides of tin, ruthenium, titanium and one or more elements selected from the group consisting of niobium, tantalum and tungsten applied to a metallic substrate, and a method for its preparation.