TY - JOUR
T1 - Catalyzed Oxidation of IG-110 Nuclear Graphite by Simulated Fission Products Ag and Pd Nanoparticles
AU - Jiang, Junhua
AU - Stempien, John
AU - Wu, Yaqiao
N1 - Jiang, Junhua; Stempien, John; and Wu, Yaqiao. (2023). "Catalyzed Oxidation of IG-110 Nuclear Graphite by Simulated Fission Products Ag and Pd Nanoparticles". Nuclear Materials and Energy, 35, 101438. https://doi.org/10.1016/j.nme.2023.101438
PY - 2023/6/1
Y1 - 2023/6/1
N2 - To evaluate the stability of nuclear materials in high temperature gas reactors under air ingress conditions, catalytic oxidation of IG-110 graphite by two simulated fission products, metallic Pd and Ag, was studied in oxidative atmosphere and at temperatures up to 1000 °C using an integrated furnace, mass spectroscopy and infrared spectroscopy system. Transmission electron microscopy and X-ray diffraction studies show that Pd and Ag nanoparticles were successfully introduced onto powdery IG-110 graphite through an impregnation and subsequent heat-treatment process. The combined mass spectroscopy and infrared spectroscopy methods allow simultaneous analysis of two gaseous products, CO and CO 2 , and separate measurements of activation energy for their formation reactions. It was found that the introduction of Pd or Ag to IG-110 graphite substantially catalyzed the oxidation of graphite, characteristic of decreased onset temperatures for the oxidation of graphite. Moreover, the catalytic effects by Pd and Ag are considerably different based on measured concentration ratios of CO 2 to CO as a function of oxidation temperatures. Ag makes the graphite oxidation commence at approximately 400 °C with CO 2 being the dominant product. In contrast, Pd significantly increases the concentration ratio of CO 2 to CO at temperatures higher than approximately 690 °C, although it decreases the onset temperature for the oxidation reaction to around 525 °C. To understand the catalytic difference, the mechanism of the graphite oxidation is discussed based on the changes of surface oxygen species on Ag and Pd.
AB - To evaluate the stability of nuclear materials in high temperature gas reactors under air ingress conditions, catalytic oxidation of IG-110 graphite by two simulated fission products, metallic Pd and Ag, was studied in oxidative atmosphere and at temperatures up to 1000 °C using an integrated furnace, mass spectroscopy and infrared spectroscopy system. Transmission electron microscopy and X-ray diffraction studies show that Pd and Ag nanoparticles were successfully introduced onto powdery IG-110 graphite through an impregnation and subsequent heat-treatment process. The combined mass spectroscopy and infrared spectroscopy methods allow simultaneous analysis of two gaseous products, CO and CO 2 , and separate measurements of activation energy for their formation reactions. It was found that the introduction of Pd or Ag to IG-110 graphite substantially catalyzed the oxidation of graphite, characteristic of decreased onset temperatures for the oxidation of graphite. Moreover, the catalytic effects by Pd and Ag are considerably different based on measured concentration ratios of CO 2 to CO as a function of oxidation temperatures. Ag makes the graphite oxidation commence at approximately 400 °C with CO 2 being the dominant product. In contrast, Pd significantly increases the concentration ratio of CO 2 to CO at temperatures higher than approximately 690 °C, although it decreases the onset temperature for the oxidation reaction to around 525 °C. To understand the catalytic difference, the mechanism of the graphite oxidation is discussed based on the changes of surface oxygen species on Ag and Pd.
KW - air ingress
KW - catalytic oxidation
KW - fission products
KW - high temperature gas reactor
KW - nuclear graphite
UR - https://scholarworks.boisestate.edu/mse_facpubs/553
M3 - Article
SN - 2352-1791
JO - Nuclear Materials and Energy
JF - Nuclear Materials and Energy
ER -