Electrochemical Conversion of CO2 to Fuels and Useful Chemicals over Metal Supported Solid Oxide Electrolyzers

Abstract

Electrochemical conversion of CO2 and H2O to fuels and chemicals provides a promising approach to simultaneously mitigate greenhouse emission and store surplus energy, which reduces electricity network variation due to increased intermittent renewable energy (such as solar and wind) utilization. Metal supported solid oxide electrolyzers (MS-SOEs) developed at Lawrence Berkeley National Laboratory provide advantages of rapid start-up, mechanical ruggedness, redox tolerance, dynamic operation, and low-cost materials. A relatively high operating temperature range of 600 to 750°C promotes energy efficiency and allows utilization of thermal energy such as steam.In this work, efficient and stable catalysts developed at the University of South Carolina have been infiltrated in the symmetrical and porous MS-SOE architecture. The phase purity has been analyzed by X-day diffraction. The morphologies of these infiltrated and posttest catalysts have been examined by scanning electron microscopy. Optimization of cell structure, processing temperature, cell voltage, and catalyst infiltration cycles for better cell performance will be presented. The stability of MS-SOEs has been evaluated during continuous operation for >200 hours. The cell degradation mechanisms revealed by electrochemical impedance spectroscopy and high-resolution scanning electron microscopy techniques will be presented.In addition to pure CO2 electrochemical conversion, effects of additional water and hydrogen in CO2 feedstock will be analyzed. Faradic efficiency and chemical selectivity calculated from gas chromatograph and electrochemical analyses will be presented.