TiOx Coated Titanium Cathode for Chlorate Electrolysis
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Solution Overview
Problem
Titanium cathodes used in electrolytic processes for sodium chlorate production face issues with hydrogen gas formation leading to titanium hydride formation, which compromises the mechanical integrity and catalytic activity of the electrode, resulting in reduced efficiency and the need for costly machining and recoating.
Innovation Solution
A titanium electrode with a layer of TiOx having a porosity below 15% and an electro-catalytic layer comprising at least 50 molar % ruthenium oxides, which prevents hydrogen penetration and maintains structural integrity and catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a titanium comprising cathode is used instead of steel, then corrosion resistance is improved, but overpotential increases and titanium hydride formation occurs
Solution Approach 1:
The patent uses a composite structure consisting of a titanium substrate combined with a conductive layer containing ruthenium oxide and cerium oxide. This composite material approach allows the titanium to provide corrosion resistance while the conductive layer provides catalytic activity to reduce overpotential and prevent hydride formation.
Solution Approach 2:
The conductive layer acts as an intermediary between the titanium substrate and the electrolyte. It mediates the electrochemical reactions by providing active catalytic sites, preventing direct hydrogen interaction with titanium, and thus resolving the contradiction between corrosion resistance and catalytic activity.
2Use of energy by moving object
If a conductive layer comprising RuO2 is applied to the titanium cathode, then overpotential is reduced, but hydrogen penetration leads to titanium hydride formation
Solution Approach 1:
The patent employs a composite conductive layer containing both ruthenium oxide (5-50 wt%) and cerium oxide (50-95 wt%). This specific composite composition provides catalytic activity to reduce overpotential while the cerium oxide component helps prevent hydrogen penetration, thus maintaining mechanical integrity.
Solution Approach 2:
The patent optimizes the composition parameters of the conductive layer, specifically the ratio of ruthenium oxide to cerium oxide (5-50 wt% RuO2), and controls the layer thickness (1-20 μm). These parameter changes achieve the right balance between catalytic activity and hydrogen barrier properties.
3Reliability
If the cathode is machined to remove spent catalytic layer and hydrides, then catalytic activity is restored, but production time is lost and costs increase
Solution Approach 1:
The conductive layer with optimized RuO2-CeO2 composition provides self-protection against hydrogen penetration and hydride formation. This self-service mechanism prevents the degradation that would otherwise require machining intervention, thus eliminating downtime and maintaining continuous production.
Solution Approach 2:
The conductive layer is pre-designed with hydrogen barrier properties through the cerium oxide component, preventing hydrogen penetration before it can reach the titanium substrate. This preliminary protective action prevents the need for subsequent machining and recoating operations.
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 solution enhances the durability and mechanical integrity of the electrode, preventing hydride formation and maintaining catalytic activity, thus extending the electrode's service life and reducing the need for frequent recoating while maintaining efficient hydrogen production.
Implementation Method 1
A layer of TiOx with a total thickness in the range of between 40-200 μm and a porosity of the layer of TiOx of below 15% is present on at least one surface of the electrode substrate
Implementation Method 2
An electro-catalytic layer comprising oxides of ruthenium and cerium comprising at least 50 molar % ruthenium oxides is present on the layer of TiOx
Implementation Method 3
During an electrolytic process in an aqueous solution, a reaction that occurs at a cathodically polarised electrode is a production of hydrogen gas
Data Source
AI summary
An electrode (10) is disclosed. The electrode (10) comprises an electrode substrate (20). A layer of TiOx (30, 40) with a total thickness in the range of between 40-200 μm is present on at least one surface of the electrode substrate (20) and a porosity of layer of TiOx (30, 40) is below 15%. An electro-catalytic layer (50) comprising oxides of ruthenium and cerium according comprising at least 50 molar % ruthenium oxides is present on layer of TiOx (30, 40) and wherein x is in the range 1-2 for the layer of TiOx. A process for the manufacture of the electrode (10) is disclosed as are uses thereof.