Electrolytic Cell Segmentation for CO2 Scrubbing
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Solution Overview
Problem
Current electrochemical systems for reducing carbon dioxide to carbon monoxide in electrolysis units face challenges in separating unreacted carbon dioxide from the product gas efficiently, as this separation process is energy-intensive and results in a product gas composition of 1:1:1 carbon monoxide to hydrogen to carbon dioxide, making it difficult to achieve low carbon dioxide levels.
Innovation Solution
A method and device that utilize a carbon dioxide electrolytic cell with separate anode and cathode compartments, where carbon dioxide is reduced in a second cathode compartment without direct contact with the catholyte, allowing the basic catholyte to absorb unreacted carbon dioxide in a gas scrubber, establishing a thermodynamic equilibrium for effective separation with minimal energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional electrolysis methods are used to reduce carbon dioxide to carbon monoxide, then carbon monoxide production is achieved, but energy-intensive separation of unreacted carbon dioxide is required
Solution Approach 1:
The cathode compartment is divided into two separate chambers: a first cathode chamber where carbon dioxide is reduced to carbon monoxide, and a second cathode chamber where unreacted carbon dioxide is absorbed by the basic catholyte. This segmentation allows simultaneous product generation and CO2 removal without energy-intensive separation processes.
Solution Approach 2:
The basic catholyte serves as an intermediary substance that selectively absorbs unreacted carbon dioxide from the product gas stream. The catholyte, already generated during electrolysis, acts as a natural absorbent that converts CO2 to carbonate/bicarbonate ions, eliminating the need for additional energy-intensive separation equipment.
2Quantity of substance
If aqueous electrolyte is used at the cathode, then carbon dioxide reduction occurs, but hydrogen formation increases due to water electrolysis
Solution Approach 1:
By segmenting the cathode compartment into two chambers separated by a membrane, the system directs carbon dioxide reduction in the first chamber while the second chamber captures unreacted CO2 with basic catholyte. This prevents hydrogen formation by avoiding direct contact between aqueous electrolyte and carbon dioxide.
Solution Approach 2:
The invention extracts the water electrolysis reaction from the carbon dioxide reduction process by using a non-aqueous or minimal-aqueous electrolyte environment in the first cathode chamber, thereby eliminating hydrogen as a byproduct while maintaining carbon monoxide production.
3Manufacturing precision
If carbon dioxide conversion is increased to improve product quality, then unreacted carbon dioxide decreases, but separation requirements increase
Solution Approach 1:
The cathode compartment is segmented into two chambers, with the second chamber serving as an integrated CO2 absorption zone. This segmentation allows the system to achieve high product quality by capturing unreacted CO2 in-situ, eliminating the need for complex external separation systems.
Solution Approach 2:
The invention merges the carbon dioxide reduction process with the unreacted CO2 absorption process into a single integrated electrolytic cell. The basic catholyte generated during electrolysis is directly used to absorb CO2 in the second chamber, combining product generation and purification in one system.
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 significantly reduces energy consumption by avoiding the need for energy-intensive heating or cooling, allows for efficient separation of unreacted carbon dioxide, and regenerates the catholyte for reuse, making the process economically favorable and improving the carbon dioxide conversion efficiency.
Implementation Method 1
Carbon dioxide is reduced to carbon monoxide at a cathode of the electrochemical cell
Implementation Method 2
The unreduced carbon dioxide is then separated from the first product gas using the basic first catholyte as absorbent
Data Source
AI summary
The present invention relates to a method and a device for the electrochemical utilization of carbon dioxide. Carbon dioxide is introduced into an electrolysis cell and is reduced at a cathode. A catholyte that has become basic in the electrolysis cell is used as an absorption agent for non-converted carbon dioxide which is contained in the product gas in addition to the carbon monoxide. The device therefore comprises two separate lines for the basic catholyte and the product gas from the electrolysis cell into a gas scrubber device. In the gas scrubber device, the catholyte and the product gas are then merged, such that the non-converted carbon dioxide is separated off.