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Conversion & storage of CO₂ using electrochemical reactors Pimlott, Douglas
Abstract
The deployment of technologies to abate CO₂ emissions is critical to address climate change. Electrochemical reactors, known as “electrolyzers”, can convert CO₂ into chemicals and fuels, or permanently store carbon as a stable mineral. These capabilities can offset emissions from heavy industry and remove historic emissions in the atmosphere. In this thesis, I demonstrate how to design electrolyzers for the capture, utilization and storage of CO₂. This thesis first focuses on the development of liquid-fed electrolyzers that convert (bi)carbonate-rich solutions from CO₂ capture units directly into carbon monoxide (CO), bypassing the need for costly CO₂ purification. I evaluate its tolerance to common flue gas impurities, such as dissolved nitrogen oxides (NOₓ) and sulfur oxides (SOₓ). While SOₓ compounds showed negligible impact, ppm-level NOₓ impurity concentrations significantly reduced CO selectivity by over 50%, due to the preferential electroreduction of NOₓ over CO₂. Next, I assess the influence of oxygen (O₂) on both liquid- and gas-fed electrolyzers. Gas-fed systems are susceptible to O₂, which causes performance loss due to O₂ reduction and cathode flooding. In contrast, liquid-fed systems show resilience due to the low solubility of O₂ in water. I then shift my focus to electrochemical mineralization pathways for permanent CO₂ storage. I first introduce an electrolyzer that uses waste sulfur (in the form of sulfite) to generate spatially separated acid and base streams at low operating voltages. These pH gradients are then used to release and carbonate reactive cations (e.g., Mg²⁺) from alkaline silicate minerals, storing CO₂ as a solid carbonate mineral. Building on this concept, I then design an electrolyzer that integrates mineral dissolution, cation transport and carbonate precipitation into a single step. This architecture eliminates the need for downstream precipitation reactors, enabling continuous operation and simplified process integration. The electrolyzer achieves stable operation at industrially relevant reaction rates. Collectively, these contributions advance the design and integration of electrochemical systems for carbon management. The results inform the development of scalable and modular electrochemical platforms capable of coupling CO₂ capture with either valorization to carbon-based chemicals and fuels, or permanent removal via the formation of geochemically stable solids.
Item Metadata
Title |
Conversion & storage of CO₂ using electrochemical reactors
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Creator | |
Supervisor | |
Publisher |
University of British Columbia
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Date Issued |
2025
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Description |
The deployment of technologies to abate CO₂ emissions is critical to address climate change. Electrochemical reactors, known as “electrolyzers”, can convert CO₂ into chemicals and fuels, or permanently store carbon as a stable mineral. These capabilities can offset emissions from heavy industry and remove historic emissions in the atmosphere. In this thesis, I demonstrate how to design electrolyzers for the capture, utilization and storage of CO₂.
This thesis first focuses on the development of liquid-fed electrolyzers that convert (bi)carbonate-rich solutions from CO₂ capture units directly into carbon monoxide (CO), bypassing the need for costly CO₂ purification. I evaluate its tolerance to common flue gas impurities, such as dissolved nitrogen oxides (NOₓ) and sulfur oxides (SOₓ). While SOₓ compounds showed negligible impact, ppm-level NOₓ impurity concentrations significantly reduced CO selectivity by over 50%, due to the preferential electroreduction of NOₓ over CO₂.
Next, I assess the influence of oxygen (O₂) on both liquid- and gas-fed electrolyzers. Gas-fed systems are susceptible to O₂, which causes performance loss due to O₂ reduction and cathode flooding. In contrast, liquid-fed systems show resilience due to the low solubility of O₂ in water.
I then shift my focus to electrochemical mineralization pathways for permanent CO₂ storage. I first introduce an electrolyzer that uses waste sulfur (in the form of sulfite) to generate spatially separated acid and base streams at low operating voltages. These pH gradients are then used to release and carbonate reactive cations (e.g., Mg²⁺) from alkaline silicate minerals, storing CO₂ as a solid carbonate mineral. Building on this concept, I then design an electrolyzer that integrates mineral dissolution, cation transport and carbonate precipitation into a single step. This architecture eliminates the need for downstream precipitation reactors, enabling continuous operation and simplified process integration. The electrolyzer achieves stable operation at industrially relevant reaction rates.
Collectively, these contributions advance the design and integration of electrochemical systems for carbon management. The results inform the development of scalable and modular electrochemical platforms capable of coupling CO₂ capture with either valorization to carbon-based chemicals and fuels, or permanent removal via the formation of geochemically stable solids.
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Genre | |
Type | |
Language |
eng
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Date Available |
2025-08-07
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0449595
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URI | |
Degree (Theses) | |
Program (Theses) | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2025-11
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International