No abstract

A new phenomenological one‐dimensional model is formulated to simulate the typical degradation patterns observed in solid oxide fuel cell (SOFC) anodes due to coal syngas contaminants such as arsenic (As) and phosphorous (P). The model includes gas phase diffusion and surface diffusion within the anode and the adsorption reactions on the surface of the Ni‐YSZ‐based anode. Model parameters such as reaction rate constants for the adsorption reactions are obtained through indirect calibration to match the degradation rates reported in the literature for arsine (AsH3), phosphine (PH3), hydrogen sulfide (H2S), and hydrogen selenide (H2Se) under accelerated testing conditions. Results from the model demonstrate that the deposition of the impurity on the Ni catalyst starts near the fuel channel/anode interface and slowly moves toward the active anode/electrolyte interface as observed in the experiments. Parametric studies performed at different impurity concentrations and operating temperatures show that the coverage rate increases with increasing temperature and impurity concentration, as expected. The calibrated model was then used for prediction of the performance curves at different impurity concentrations and operating temperatures. Good agreement is obtained between the predicted results and the experimental data reported in the literature.

for good times we had together. Special thanks to Raju for his outstanding help and patience to my never ending questions. Special thanks to my parents Asuman and Omer Faruk Cayan and my sister Neval Cayan for their great support, encouragement and unshakable faith in me although they are thousands of miles away. Lastly, I want to express my incommensurable love to my husband Ertan Karaismail, my soul mate, for his understanding, endless patience and encouragement when it was most required. And most of all, final thanks go to my son Dağhan Ali Karaismail, who made me a better person. vi

No abstract

Degradation of the Ni/yttria‐stabilised zirconia (YSZ) anode of the solid oxide fuel cell has been evaluated in the coal syngas containing different PH3 concentrations in the temperature range from 750 to 900 °C. Thermodynamic equilibrium calculations show that PH3 in the coal syngas gas is converted mostly to P2O3 at 750–900 °C. The phosphorous impurity reacts with the Ni‐YSZ anode to form phosphates. The P‐impurity poisoning leads to the deactivation of the Ni catalyst and to the reduction in the electronic conductivity of the anode. The impurity poisoning effect on the anode is exacerbated by increase in the temperature and/or the PH3 concentration.