Development of Integrated Carbon Dioxide Capture and Conversion for Sustainable Chemical Production
Date
2023-03-30
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Abstract
The electrochemical CO2 reduction reaction (eCO2RR) is a scalable, flexible, compact, and energy-efficient route to convert CO2 into value-added products. However, the viability of eCO2RR relies on reducing energy demands and production costs to compete with established alternatives. Integration of CO2 capture and conversion, where the capture system is unified with eCO2RR, has the potential to eliminate energy-intensive steps of CO2 capture and regeneration, leading to improved process economics. The first part of this study conducted a comprehensive review of available literature to identify the potential sources of CO2 and the relevant capture technologies. The second part focuses on using ambient air to capture CO2 using direct air capture (DAC) technology using alkali-hydroxide-based solvent to produce carbonate and converting carbonate into an electrochemical system. The concept of carbonate electrolysis was explored as a method for regenerating the capture solvent while converting CO2 to carbon monoxide (CO). It was found that the electrochemical cell could serve as both a solvent regeneration and CO2 conversion step. Our modeling study showed a trade-off between the regeneration and CO2 conversion step. However, the techno-economic analysis (TEA) showed that with technological advancements, the production cost of CO could drop below 200 $/ton CO compared to the current production cost over 1500 $/ton CO. The third chapter focused the on direct electrolysis of CO2 from a dilute stream to simulate industrial flue gasses. A permselective gas diffusion electrode (PGDE) consisting of a metal-organic framework-based permselective layer and a silver-based gas diffusion electrode (GDE) was designed. The PGDE enables in-situ CO2 capture and electrochemical conversion. A comparative study of various PGDEs was performed to find the optimum conditions. With 10% CO2 purity in the feedstock, the CALF-20/PSF-based PGDE delivered a 5-fold increased maximum partial current density compared to the unmodified GDE. In addition, it was able to perform continuously for more than 20 hours and retained around 70% FE for CO. In conclusion, this thesis provides an understanding of the efficiency trade-off between CO2 capture and conversion and identifies pathways for optimizing efficiency. The integration of CO2 capture and conversion reduces the need for energy-intensive steps and has the potential to lower the production costs of CO2 derived chemical feedstocks.
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Keywords
Carbon dioxide, CO2 reduction, CO2 conversion, Renewable chemicals and fuels, Carbon capture and conversion, CO2 capture, Electrochemical CO2 conversion, Electrochemical CO2 reduction, Direct air capture, DAC
Citation
Shaker Shiran, H. (2023). Development of integrated carbon dioxide capture and conversion for sustainable chemical production (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.