Development of scalable electrochemical systems and devices for electrified chemical production
Date
2025
Authors
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Journal ISSN
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Publisher
University of Delaware
Abstract
Electrochemical production of power, chemicals, and food represents a promising approach to offset greenhouse gas emissions and improve the general quality of life. Electrochemical systems and devices can be constructed in such a way that they can address a wide variety of needs. Of these various systems, power generation through fuel cells and CO2 electroreduction to both chemicals and food production feeds are of great interest. In this work, I will discuss my research efforts to tackle these key areas of need through electrochemical device development. ☐ The first portion of this dissertation will focus on my work to develop selective and stable catalysts for complete ethanol electrooxidation. Through novel catalyst synthesis approaches, ordered multi-principal element intermetallic nanoparticles were synthesized, containing upwards of 8 different elements. It was found that the nanoparticles consisting of (Pt0.8Pd0.1Au0.1)(Fe0.6Co0.1Ni0.1Cu0.1Sn0.1) were 12.5 times more active than commercial Pt/C catalysts for complete ethanol oxidation. Additionally, these particles were significantly more stable and showed no evidence of degradation after accelerated durability testing. Therefore, (Pt0.8Pd0.1Au0.1)(Fe0.6Co0.1Ni0.1Cu0.1Sn0.1) multi-metallic nanoparticles present a promising route to improve the cost-effectiveness of ethanol fuel cells through lowered catalysts loading and increased catalyst lifetimes. Additionally, this novel synthesis process could be used to produce tailored catalysts for future electrochemical applications. ☐ Next, I will discuss my reasoning for moving away from single-reaction systems towards tandem and hybrid systems, specifically for CO2 electroreduction. Low-temperature CO2 and CO electroreduction systems suffer from low technology readiness (a scale from 1 to 9, with 1 being lab scale and 9 being an industrial process) and produce low-cost commodity chemicals. Due to these issues, CO2/CO electroreduction systems require significant development before being competitive with current industrial production routes. This work discusses the improved feasibility of developing tandem CO2/CO electroreduction systems to accelerate deployment. It was found that by coupling CO2/CO electroreduction with either mature processes or tailoring the systems to work with downstream upgrading to higher-value specialty chemicals, CO2/CO electroreduction could reach technological maturity on a much shorter time scale. Possible routes are discussed, such as reactive CO2 capture, CO2 electroreduction coupled with biological upgrading, and CO electroreduction coupled with thermochemical CO production. ☐ With the motivation of producing tandem and hybrid CO2 systems, the third portion of this dissertation will explore my research on developing a hybrid electrochemical-biological system for food production via artificial photosynthesis. In this work I developed a tandem CO2-to-CO and a CO-to-acetate electroreduction system. This system achieved state-of-the-art acetate production from a direct CO2 feed, achieving >25% of fed CO2 to acetate. The acetate stream was then tailored to maximize biological growth by modifying the fed acetate-to-electrolyte ratio. The electrolyte was shown to be capable of growing photosynthetic algae and common food fungi such as yeast and mushrooms without sunlight at efficiencies four times greater than direct photosynthesis. Additionally, this study found that electrochemically produced acetate could be incorporated into the metabolism of multiple common crops, such as lettuce and rice, showing the potential for future sunlight-free food production via a coupled electrochemical-biological approach. ☐ Once it was demonstrated that acetate could be produced selectively for food production, my goal shifted to create a more broadly applicable acetate production stream from CO electroreduction. The fourth portion of this dissertation will focus on my work to generate an easily separable acetate product stream from direct CO electroreduction to be used in commercial applications. I will highlight my work on developing a stable membrane electrode assembly CO electrolyzer for producing concentrated acetate product streams. Through reactor, membrane, and catalyst design, this system demonstrated state-of-the-art acetate production from CO, producing >3 M acetate at a purity of 98% for >100 hours of operation. This system also produced a peak acetate concentration of 7.7 M (57 wt%) at a molar purity of 99.3%, both the highest weight percent and purity reported. Our techno-economic analysis suggests that this concentration and purity can reduce the separation energy demand by 5-fold compared to other CO reduction electrolyzers. ☐ Lastly, after the feasibility of CO electroreduction to acetate was proven for both food and chemical production at the lab scale, the next step was to scale this system to the pre-pilot scale. The last section of this work will focus on my scaling efforts for CO2/CO electroreduction to produce a kW scale stack capable of producing >1 kg of acetate per day. I will discuss my design strategy in manufacturing the electrolyzer stack, flow pattern analysis, cooling water employment, and catalyst development for improved durability at larger scales. Lastly, the demonstration of the system for extended operation will be discussed, as well as future research directions to push this system past 1 kW and toward industrial readiness.
Description
Keywords
Carbon dioxide, Carbon monoxide, Catalysis, Electrochemistry, Fuel cells, Reactor development