Sulphur Depolarized Electrolysis with Proton Membrane for Halogen Control
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Solution Overview
Problem
Existing methods for hydrogen production from non-purified water, such as seawater, face inefficiencies due to halogen evolution reactions occurring at lower voltages than oxygen evolution, leading to unsustainable electrolysis cells and lower efficiency.
Innovation Solution
A method and device using sulphur depolarized electrolysis (SDE) with a proton conductive membrane and controlled voltage application between 0.45 V and 1.37 V, combined with sulphur dioxide oxidation and proton reduction, to produce hydrogen gas and sulphuric acid efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional PEM water electrolysis is used with non-purified water, then hydrogen production is possible, but halogen evolution reactions occur at lower voltages than oxygen evolution, making the electrolysis cell unsustainable
Solution Approach 1:
The patent introduces a proton-selective membrane as an intermediary between the anode and cathode compartments. This membrane selectively transports protons while blocking halide ions, preventing them from reaching the cathode where they would undergo evolution reactions. The membrane acts as a mediator that allows necessary ion transport while blocking harmful species, enabling sustainable operation with non-purified water.
Solution Approach 2:
The electrolysis cell is divided into separate anode and cathode compartments by the proton-selective membrane. This segmentation isolates the reaction zones, allowing different electrochemical reactions to occur independently in each compartment. The membrane creates distinct environments where halide evolution is prevented at the cathode while oxygen evolution occurs at the anode, resolving the contradiction between productivity and reliability.
2Reliability
If alkaline electrolysers are used to prevent halogen evolution reactions, then cell sustainability is improved, but realizable cell efficiency decreases
Solution Approach 1:
The patent changes the operating parameters by using a proton-selective membrane that enables operation at lower pH values compared to traditional alkaline electrolysers. This parameter change allows the system to prevent halogen evolution through physical separation rather than relying on high pH conditions, thereby maintaining both cell sustainability and higher electrical efficiency associated with PEM technology.
3Ease of manufacture
If non-purified water is used directly in electrolysis, then water purification costs are reduced, but halogen evolution reactions occur leading to lower efficiency
Solution Approach 1:
The proton-selective membrane serves as an intermediary barrier that allows the system to use non-purified water without suffering from halogen evolution. The membrane selectively permits proton passage while blocking halide ions, enabling direct use of inexpensive non-purified water while maintaining high electrolysis efficiency by preventing competing side reactions.
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
Enables stable hydrogen production with improved efficiency by preventing halogen evolution, allowing for safe and effective electrolysis without hazardous by-products.
Implementation Method 1
a proton conductive membrane, wherein the proton conductive membrane is configured to allow passage of protons and water molecules therethrough
Implementation Method 2
sulphur dioxide, which was received by the sulphur dioxide supply means, reacting with water molecules, which diffused through the membrane from the cathode side to the anode side
Implementation Method 3
produces hydrogen gas at the cathode side via reduction of protons conducted through the proton conductive membrane from the anode side to the cathode side, wherein said reduction is enabled by recombination of protons with electrons
Implementation Method 4
produces sulphuric acid at the anode side via oxidation of sulphur dioxide at the anode, said oxidation is enabled by sulphur dioxide, which was received by the sulphur dioxide supply means, reacting with water molecules
Implementation Method 5
applying a voltage of at least 0.45 V and up to 1.37 V to the electrodes of the electrochemical cell, said voltage is provided by an external power source and transmitted to the electrodes of the electrochemical cell via the electrical connection means, to cause an electrolysis reaction
Data Source
Figure 1~2
Figure 3
Figure 4~5a
AI summary
A method for producing hydrogen gas from non-purified water via sulphur depolarized electrolysis (SDE), said method comprises the steps of providing at least one electrochemical cell (2), which comprises at least one positive electrode (A) and at least one negative electrode (C), separated by a proton conductive membrane (3), non-purified water supply means (51) configured to supply non-purified water to the cathode, sulphur dioxide supply means (S2) configured to supply sulphur dioxide to the anode, electrical connecting means (4) configured to connect the anode (A) and the cathode (C) to an external power source (P), supplying non-purified water to the cathode, supplying sulphur dioxide to the anode, applying a voltage of at least 0.45 V and up to 1.37 V to the electrodes (A, C) to cause an electrolysis reaction that produces hydrogen gas at the cathode and sulphuric acid at the anode, removing produced hydrogen gas from the cathode and produced sulphuric acid from the anode.