Oxygen-Consuming Electrode Using Silver Oxide Precipitation
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Solution Overview
Problem
Existing oxygen-consuming electrodes for chlor-alkali electrolysis face challenges such as high operating voltage, limited long-term stability, and high production costs, particularly with carbon-supported platinum and silver catalysts, which suffer from mechanical instability and oxidation issues.
Innovation Solution
A method for producing an oxygen-consuming electrode using finely divided silver oxide, where silver oxide is precipitated, filtered, washed, dried, and then processed with a fluorine-containing polymer and an electrically conductive carrier to create a catalyst coating with improved mechanical stability and reduced operating voltage, utilizing a silver oxide with specific surface area and particle size characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon-supported platinum or silver catalysts are used, then catalytic activity for oxygen reduction is achieved, but mechanical stability and long-term durability deteriorate due to oxidation of the support material
Solution Approach 1:
The invention extracts the catalyst from the carbon support structure and uses finely divided metallic silver or silver oxide particles as standalone catalysts without carbon support. This eliminates the oxidation problem of the carbon support while maintaining catalytic activity, thereby resolving the contradiction between achieving catalytic function and maintaining mechanical stability.
Solution Approach 2:
The invention uses inexpensive metallic silver or silver oxide instead of expensive platinum on carbon support. The simple metallic silver structure avoids the complexity and instability of carbon-supported catalysts, providing long-term mechanical stability without requiring a protective carbon matrix.
2Reliability
If high silver concentration is used in the catalyst coating, then catalytic activity improves, but production cost increases
Solution Approach 1:
The invention optimizes the silver concentration parameter to a specific range (2-10 g/m²) that provides sufficient catalytic activity while minimizing material cost. This parameter optimization resolves the contradiction between achieving high catalytic activity and controlling production costs.
Solution Approach 2:
The invention replaces expensive platinum with inexpensive silver or silver oxide, achieving comparable catalytic activity at much lower cost. The use of metallic silver without expensive carbon support further reduces material costs while maintaining effectiveness.
3Loss of energy
If operating voltage is reduced to improve energy efficiency, then energy consumption decreases, but electrode performance and stability may be compromised
Solution Approach 1:
The invention changes the electrode structure parameters by using finely divided silver oxide or metallic silver with specific surface area characteristics, which enhances catalytic efficiency and reduces operating voltage without compromising electrode performance or stability.
Solution Approach 2:
The invention creates a composite catalyst system combining silver oxide with metallic silver particles, where the silver oxide provides high surface area for catalysis and the metallic silver ensures electrical conductivity and stability, achieving low operating voltage with maintained performance.
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 method results in a lower cell voltage and enhanced long-term stability of the oxygen-consuming electrode, overcoming the limitations of previous technologies by maintaining mechanical stability and reducing production costs.
Implementation Method 1
Precipitation of silver oxide by adding a silver salt solution, preferably a silver nitrate solution, to an alkaline solution, in particular an aqueous NaOH solution
Implementation Method 2
drying of the silver oxide, the silver oxide initially being heated at a temperature in the range from 80 to 200° C., preferably at 100 to 120 °C.
Implementation Method 3
the silver oxide initially being heated at a temperature in the range from 80 to 200° C., preferably at 100 to 120 °C., in particular for up to 10 hours
Implementation Method 4
the gas diffusion layer having at least one fluorine-containing polymer, silver in the form of silver particles and silver oxide in the form of silver oxide particles
Data Source
AI summary
Producing (P1) an oxygen-consuming electrode, involves: precipitating silver oxide by metering silver salt solution to an initial charge of an alkaline solution and then stirring suspension over a period of at most 10 minutes, in the course of which the temperature of suspension is kept at 10-50[deg] C; removing precipitated silver oxide from suspension; drying silver oxide at 80-200[deg] C, optionally under reduced pressure; and processing resulting silver oxide with an electrically conductive support material, catalyst comprising silver particles, and finely divided fluorinated polymer. Producing (P1) an oxygen-consuming electrode, involves: (a) precipitating silver oxide by metering a silver salt solution to an initial charge of an alkaline solution and then stirring the suspension over a period of at most 10 minutes, in the course of which the temperature of the suspension is kept at 10-50[deg] C; (b) removing the precipitated silver oxide from step (a) from the suspension; (c) drying the silver oxide at a temperature of 80-200[deg] C, optionally under reduced pressure; and (d) further processing the resulting silver oxide with an electrically conductive support material, a catalyst comprising silver particles, and a finely divided fluorinated polymer to give a flat oxygen-consuming electrode. Independent claims are included for the following: (1) an oxygen-consuming electrode at least comprising an electrically conductive support, an electrical contact site, and a gas diffusion layer containing a catalytically active component, where the gas diffusion layer comprises at least one fluorinated polymer, silver in the form of silver particles and silver oxide in the form of silver oxide particles, produced by the process (P1); and (2) an electrolysis cell for the electrolysis of an alkali metal chlorides, comprising the oxygen-consuming electrode (T1) as the cathode.