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Electrochemical synthesis of carboxylic acids from carbon dioxide
Date
2025
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
An immediate solution is needed to abate ramifications from global warming caused by high concentrations of atmospheric CO2. An economically viable solution is to redefine waste CO2 emissions as a usable feedstock via CO2 electrolysis. CO2 electrolysis involves using electricity to reduce CO2 into fuels and chemical feedstocks. In particular, carboxylic acids, specifically formic acid and acetic acid, are of interest due to their compatibility in bioreactors for plastic, pharmaceutical, and food production. This dissertation is focused on improvement of electrochemical conversion of CO2 into carboxylic acids. ☐ In Chapter 2, improvements for a tandem CO2 to carbon monoxide to acetate system is investigated. First, the material properties of anion exchange membranes are connected to the resulting carbon monoxide electrolysis performance. The selectivity towards acetate is improved by up to 15% through synergistic coupling of anion exchange membranes with high ethanol crossover and partial ethanol oxidation promoting anodes. In addition, membranes with the same backbone and different pendant groups were compared to gain insight into improved molecular design of anion exchange membranes for carbon monoxide electrolysis. Improvements to hardware design for scale-up CO2 and carbon monoxide electrolyzers, focused on sealing, compression, and flow dynamics, are also discussed. ☐ Chapter 3 and Chapter 4 discussed alternative electrolyzer architectures for high purity carboxylic acid production. Chapter 3 is focused on diagnostics of a porous solid electrolyte architecture that utilizes a packed ionic resin interlayer for recombination of carboxylates with protons. The packed resin interlayer is redesigned into a single ionomer wafer and gasketting is redesigned to ensure uniform fluid flow for improved consistency. Diagnostics focused on key interfaces in the electrolyzer was utilized to identify that high contact anion conducting interfaces is required for lower overpotential operation in deionized water. Two solutions are presented to improve interfacial contact at anion conducting interfaces to demonstrate low overpotential operation. ☐ Chapter 4 is focused on improving a perforated bipolar membrane architecture for concentrated formic acid production. The formic acid removal at the anode is improved through an interdigitated flow pattern and increasing convection induced by momentum. The effluent concentration was improved from 0.1 M in the previous publication on this architecture to 3.78 M using the improved operating conditions. In addition, the reactor is scaled from 25 cm2 to 400 cm2 by designing a mechanically robust perforation design. ☐ In summary, significant improvements towards electrochemical synthesis of carboxylic acids from CO2 is demonstrated, further advancing the economic viability of this technology. Chapter 5 discusses remaining gaps in knowledge and future research opportunities in the field to develop economical CO2 electrolyzers.
Description
"At the request of the author or degree granting institution, this graduate work is not available to view or purchase until August 10 2026."--ProQuest abstract/details page.
Keywords
Electrochemistry, Global warming, Carboxylic acids