EAGER: Electrochemical Reactor for Spontaneous Power Generation and CO2 Capture

University Of Connecticut, Storrs CT

Investigators

Abstract

1005303 Mustain The objective of this project is to test the hypotheses that: i) alkali earth oxides with the pyrochlore structure can selectively reduce O2 and atmospheric CO2 to CO3-2 in an alkaline electrochemical reactor; ii) operating the reactor with carbonate anions reduces the degradation of stateof- the-art anion exchange membranes compared with operation on the hydroxide cycle; and iii) H2 and methanol can be electrochemically oxidized on Pt surfaces with carbonate anions. These fundamental discoveries will allow for the development of a room temperature electrochemical reactor operating on the carbonate anionic cycle with reduced cost and increased durability compared to both the proton and hydroxide exchange membrane fuel cells. In addition to producing energy, this cell also acts as a CO2 ?pump? and purification device. The anode effluent CO2 and water can be separated and either utilized in chemical processing or sequestered. In this work, three pyrochlore structured (A2B2O7) oxygen reduction electrocatalysts will be tested: Ca2Pt2O7, Ca2Ru2O7 and Ca2W2O7. A calcium-based oxide was selected due to the known surface basicity of its root oxide, CaO, which will allow for the preferential adsorption of CO2 over H2O on the catalyst surface. The pyrochlore structured oxide avoids common pitfalls of alkali earth oxides, including low electronic conductivity and the formation of surface passivating species. Pt, Ru and W ?B? metals will be investigated because of their ability to activate molecular oxygen in alkaline media. The resulting catalysts will be fully characterized by SEM/EDS, XRD, BET and XPS. Pt electrocatalysts will be investigated at the anode, where two common fuels, H2 and CH3OH, will be oxidized and their kinetics examined. All electrochemical measurements will be conducted in a custom-built three electrode cell. Finally, the chemical stability and ionic conductivity of six commercially available anion exchange membranes will be investigated in the presence of both concentrated KOH and HCO3-/CO3-2. The results will yield information regarding surface adsorption and electron transfer behavior of the cathode oxides, information regarding electrochemical reactor design, specifically the construction, maintenance and stabilization of the electrochemical interface. Also, the PI will use the individual components to construct a laboratory scale, 5 cm2 electrochemical reactor operating on the carbonate cycle and demonstrate its performance under various operating conditions. Broader Impacts The educational objective is to establish a teaching and learning chain related to electrochemical science and engineering within the PI?s group at the University of Connecticut. This will: i) involve an undergraduate student in the research activities; ii) train a graduate student; iii) permit hands-on research in the PI?s laboratory for a Hartford Public School secondary school teacher through the NSF-sponsored Joules-Fellows program at the University of Connecticut; and iv) disseminate the scientific advances in archival journals. The research and educational activities will enhance discovery and understanding while promoting teaching, training and learning across multiple levels. Also, the results could have far reaching impact on many important systems including: fuel cells, batteries, heterogeneous transesterfication of oils for biodiesel, electrochemically assisted carbon sequestration, reduction of nitrous oxides in automotive pollution prevention and water treatment and electrolysis. Success in this regard could catalyze a transformative shift in philosophy regarding electrochemical energy generation devices, renew public, private and legislative support for alternative energy technologies and yield a cost-effective, environmentally green energy source with the potential for a net negative CO2 footprint for the 21st century and beyond.