Catalyzed Cushion Layer Reduces Hydrogen Overpotential
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Solution Overview
Problem
Existing electrochemical processes, such as the chlor-alkali process, face high power consumption and health/environmental risks due to the use of mercury, with conventional zero-gap membrane cells relying on platinum catalytic coatings, which are costly and limited to the fine mesh layer, neglecting the potential catalytic activity of the cushion layer.
Innovation Solution
A zero-gap electrode assembly with a flexible, catalytically coated fine mesh and cushion layer using non-platinum metals like cobalt, gold, iridium, osmium, palladium, rhenium, rhodium, or silver, applied in situ to increase the electrolytically active area and reduce cell voltage, along with a method of applying catalyst precursors to these components during electrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If platinum catalytic coatings are applied only to the fine mesh layer, then the cost is reduced, but the electrolytically active area is limited and hydrogen overpotential remains high
Solution Approach 1:
The patent combines catalytic coatings on both the fine mesh layer and the cushion layer into a unified catalytic system. This merging of catalytic functions across multiple layers significantly increases the total electrolytically active area and reduces hydrogen overpotential by providing multiple sites for efficient hydrogen evolution reactions.
Solution Approach 2:
The patent extends catalysis from the traditional two-dimensional fine mesh surface to include the three-dimensional cushion layer volume. By applying catalytic coating to the cushion layer which has substantial thickness and surface area, the patent utilizes an additional dimensional space for catalytic activity, thereby increasing the overall active area without confining catalysis to a single thin layer.
2Ease of manufacture
If non-platinum metals are used for catalytic coatings, then the cost is reduced, but the catalytic activity may be lower than platinum
Solution Approach 1:
The patent changes the parameters of the catalytic system by substituting platinum with non-platinum metals such as nickel, cobalt, or iron. These alternative metals offer cost advantages while maintaining acceptable catalytic activity for hydrogen evolution, particularly when applied in greater quantities across both the fine mesh and cushion layers.
Solution Approach 2:
The patent employs composite catalytic structures where non-platinum metals are applied as coatings on the electrode substrates. This composite approach combines the structural integrity of the substrate with the catalytic properties of the non-platinum metal coating, achieving a balance between cost and catalytic performance.
3Reliability
If the cushion layer is made compressible to maintain contact with the membrane, then the electrical contact resistance increases, but the membrane contact is maintained
Solution Approach 1:
The patent applies different properties to different parts of the electrode assembly. The cushion layer is made compressible locally to ensure membrane contact, while the fine mesh layer maintains its electrical conductivity for current flow. This local differentiation of properties allows the system to simultaneously achieve good membrane contact and acceptable electrical conductivity.
Solution Approach 2:
The cushion layer acts as an intermediary between the rigid support structure and the membrane. Its compressibility allows it to adapt to membrane movements and maintain contact, while its conductive properties enable it to serve as an electrical pathway, mediating between mechanical compliance and electrical conductivity requirements.
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
Significantly lowers the hydrogen overpotential by 30 mV to 400 mV and reduces cathodic voltage by 20% to 50% compared to uncatalyzed cells, demonstrating the effectiveness of non-platinum catalytic coatings on both the fine mesh and cushion layers in reducing energy consumption.
Implementation Method 1
The cushion layer may have a catalytic coating consisting essentially of one or more of cobalt, gold, iridium, osmium, palladium, rhenium, rhodium, or silver
Implementation Method 2
the electrolysis of brine solutions, and has been practiced commercially since the end of the nineteenth century
Data Source
AI summary
A zero-gap electrode is taught herein having a non-platinum containing catalytic coating that can be applied ex situ or in situ and that significantly reduces hydrogen overpotential. Moreover, the electrode taught herein includes a catalyzed fine mesh layer, cushion layer, and rigid backing.