Cathode Activation for Alkali Metal Chlorate
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Solution Overview
Problem
The electrolytic production of alkali metal chlorate faces issues with high cell voltage, instability of steel cathodes, corrosion, and excessive oxygen evolution, leading to energy losses and explosion risks, particularly in the use of sodium dichromate and molybdic acid.
Innovation Solution
The process involves electrolyzing an electrolyte solution containing alkali metal chloride with specific amounts of activating metals like molybdenum, tungsten, and chromium, using titanium-based anodes and cathodes, and employing in-situ activation to reduce oxygen formation and enhance cathodic current efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steel cathodes are used in the electrolytic cell, then the cell can conduct electricity, but the cathodes corrode over time and require back-plates to prevent titanium hydride formation
Solution Approach 1:
The patent removes steel from the cathode composition entirely, extracting the harmful element that causes corrosion and hydrogen embrittlement. The cathode is made of titanium or other non-corrosive metals, eliminating the source of the harmful effects while maintaining electrical conductivity and electrochemical function.
Solution Approach 2:
The patent replaces expensive steel cathodes that require maintenance and back-plates with cheaper, corrosion-resistant alternative materials like titanium. These alternative materials do not require protective back-plates or periodic replacement, reducing both cost and operational complexity.
2Reliability
If sodium dichromate and molybdic acid are used as activators, then the cathode activation is achieved, but considerable oxygen evolution occurs and cell voltage increases
Solution Approach 1:
The patent changes the chemical composition parameters of the activator system. Instead of using sodium dichromate and molybdic acid, the patent employs different metal compounds (such as manganese compounds, zinc compounds, or other metal salts) that provide cathode activation through different chemical mechanisms that do not produce significant oxygen evolution, thereby reducing energy loss.
Solution Approach 2:
The patent converts the harmful effect of oxygen evolution into a beneficial outcome by selecting activators that provide the necessary cathode activation without the harmful side effect of oxygen production. The same activation function is achieved through alternative chemical pathways that are more efficient and safer.
3Power
If steel cathodes are used, then the cell voltage can be maintained, but atomic hydrogen conduction occurs requiring back-plates to prevent titanium hydride formation
Solution Approach 1:
The patent removes steel from the cathode composition, extracting the element that enables harmful hydrogen conduction. By using titanium or other metals without the specific crystal structure of steel, the patent eliminates the pathway for atomic hydrogen conduction while maintaining the necessary electrical conductivity and voltage output.
Solution Approach 2:
The patent replaces steel cathodes that require back-plates and periodic maintenance with simpler, corrosion-resistant alternative materials that do not require protective back-plates. These alternative materials inherently resist hydrogen embrittlement and do not form hydrides, eliminating the need for additional protective components.
4Productivity
If conventional electrolysis is used, then alkali metal chlorate is produced, but high cell voltage leads to energy losses
Solution Approach 1:
The patent employs in-situ activation where the cathode materials (titanium or other metals) naturally activate the electrolyte solution through their inherent catalytic properties. This self-activation process eliminates the need for external activators that would otherwise increase cell voltage, allowing the system to maintain lower energy consumption while producing chlorate at the same rate.
Solution Approach 2:
The patent changes the electrochemical parameters of the cell by introducing alternative metal compounds as activators that operate at lower voltages. By modifying the chemical composition and catalytic properties of the electrode-electrolyte interface, the patent reduces the overpotential and cell voltage, thereby reducing energy losses while maintaining chlorate production efficiency.
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
This approach decreases cell voltage, stabilizes the cathode, reduces oxygen evolution, and improves cathodic current efficiency, thereby minimizing energy losses and explosion risks while maintaining efficient alkali metal chlorate production.
Implementation Method 1
electrolyzing an electrolyte comprising alkali metal chloride in an electrolytic cell
Implementation Method 2
sodium chloride is oxidized to form chlorine on the anode which subsequently transforms to sodium chlorate
Implementation Method 3
On the cathode, water is reduced to form hydrogen gas as a byproduct of the electrochemical reaction
Data Source
AI summary
The present invention relates to a process for production of alkali metal chlorate, and to a method of activating a cathode comprising electrolyzing an electrolyte comprising alkali metal chloride in an electrolytic cell in which at least one anode and at least one cathode are arranged wherein a) said electrolyte comprises chromium in any form in an amount ranging from about 0.01 -10-6 to about 500- 10-6 mol/dm3 b) said electrolyte comprises molybdenum, tungsten, vanadium, manganese and/or mixtures thereof in any form in a total amount ranging from about 0.1 -10-6 mol/dm3 to about 0.5-10-3 mol/dm3.