Solid oxide fuel cells (SOFCs) are attractive devices for power generation due to their fuel flexibility. Determining the mechanisms of fuel consumption and product formation on electrode surfaces is important for understanding and devising strategies for higher cell performance. In situ spectroscopic methods are, however, challenging because of the high temperatures (&gt; 700 °C) required for SOFC operation. We have developed real-time, operando infrared emission, near infrared thermal imaging and Raman spectroscopy to study processes occurring in SOFCs. Combined with ex situ infrared spectroscopy and mass spectrometry of the products, along with concurrent electrochemical measurements we are able to obtain a comprehensive picture of the effects of contaminants and remediation approaches. The effects of various mixtures of H2 and O2 in Ni-YSZ SOFCs operating on methane have been explored to clarify processes pertinent to carbon removal. Our results suggest that under oxidative conditions, realized with CH4 + O2 mixtures, oxygen quickly reacts with hydrogen to form water. As a consequence, carbon reforming processes effectively reduce to steam reforming at the anode with a prominent role of surface bound hydroxyl. We also report initial studies of the effects of sulfur based on SOFC operation with methane and &lt; 200 ppm H2S which indicates that sulfur poisoning is promoted in electrochemically active regions in contrast to conditions that favor coking. The results for sulfur are compared to similar studies for chlorine degradation to identify common themes.

Operando studies of carbon removal and contaminants in solid oxide fuel cells

2019 Spring National Meeting

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