Selective Cathode for Electrolytic Chlorate Process
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Solution Overview
Problem
The existing electrolytic chlorate process requires the use of sodium dichromate, which is highly toxic and poses environmental and health risks.
Innovation Solution
The process involves using a non-divided electrolytic cell with a cathode comprising a conductive electrode substrate coated with intermediate conductive layers and an electrocatalytic top layer made of cerium oxide and/or manganese oxide, eliminating the need for added chromium and sodium dichromate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sodium dichromate is added to the electrolyte to minimize unwanted reduction reactions on the cathode, then selectivity for hydrogen evolution is improved, but environmental harm and health risks increase due to the high toxicity of chromium substances
Solution Approach 1:
The patent extracts and removes the harmful chromium-based selective cathode layer from the system. Instead of using sodium dichromate to form a chromium (III) oxide/hydroxide layer on the cathode, the invention employs a chromium-free electrolyte and a cathode with a selective layer composed of other materials that prevent unwanted reduction reactions without introducing toxic substances.
Solution Approach 2:
The patent replaces the persistent toxic chromium layer with a non-toxic, easily replaceable selective cathode layer. The new selective layer materials are environmentally friendly and can be disposed of or regenerated without environmental harm, effectively treating the selective layer as a consumable component that does not persist in the environment.
2Reliability
If a selective cathode layer is formed using chromium-based substances, then unwanted reduction reactions are minimized, but the complexity of the process increases due to the need to manage toxic chemical additions
Solution Approach 1:
The patent removes the chromium-based substances and associated process complexity from the system. The selective cathode layer is formed using non-toxic materials, eliminating the need to manage toxic chemical additions, storage, handling, and disposal procedures.
Solution Approach 2:
The selective cathode layer in the patent is designed to form automatically on the cathode surface through electrochemical processes without requiring manual addition of chromium-based substances. The layer self-regulates and maintains its selective properties without external intervention, simplifying the overall process.
3Productivity
If conventional electrolytic cells are used with chromium-based additives, then chlorate production efficiency is maintained, but environmental sustainability deteriorates due to toxic chemical usage
Solution Approach 1:
The patent replaces persistent toxic chromium additives with non-toxic, environmentally benign selective cathode layer materials that can be easily replaced or regenerated. This allows maintaining production efficiency while eliminating environmental harm from toxic chemical accumulation.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte and selective cathode layer from chromium-based to chromium-free materials. This parameter change maintains the functional properties needed for efficient chlorate production while eliminating the harmful environmental effects of toxic chemicals.
Data Source
AI summary
The present disclosure relates to a process for the production of alkali metal chlorate in a single compartment electrolytic cell, which avoids the need for addition of sodium dichromate to the process, in which unwanted side-reactions are reduced by using a cathode having an electrocatalytic top layer on a substrate that optionally also has one or more intermediate layers. The top electrocatalytic layer comprises an oxide of manganese and/or cerium.