Catalytic Oxygen Storage Materials

  • Authors: D. Chen, S. R. Bishop, M. Kuhn, H. L. Tuller (in collaboration with R. Moos, University of Bayreuth, Germany)
  • Sponsorship: NSF - Materials World Network

Combustion of fossil fuels, essential for electricity generation and vehicular propulsion, is generally incomplete, leading to harmful NOx, CO, and unburned hydrocarbon emissions. Progress in minimizing such emissions has relied on the operation of “three-way catalysts” (TWCs), which utilize a combination of precious metals and metal oxides with the ability to take up or release oxygen for reduction/oxidation of pollutants (NOx to N2 and CO & HC to CO2 & H2O, respectively). In this project, we investigate the rate at which oxygen storage materials (OSM, typically CexZr1-xO2-δ) exchange oxygen with the atmosphere and the magnitude of oxygen that they store with the aid of geometrically well-defined thin film structures. Impedance spectroscopy; Kelvin probe; and thermogravimetry, Raman scattering, and electrical conductivity measurement methods are used to determine electrochemical performance and oxygen storage capabilities. These properties, when correlated to actual TWC performance using a differential flow reactor, will allow for a more detailed understanding of performance criteria. Previous studies on PrxCe1-xO2 in our group have demonstrated the feasibility of these approaches[1][2][3][4][5].

  1. P. Forzatti, L. Castoldi, I. Nova, L. Lietti, and E. Tronconi, “NOx removal catalysis under lean conditions,” Catalysis Today, vol. 117, no. 1–3, pp. 316–320, Sep. 2006. [↩]
  2. M. Kuhn, S. R. Bishop, H. L. Tuller, and J. L. M. Rupp, “Structural characterization and oxygen nonstoichiometry of ceria-zirconia Ce1-xZrxO2-δ  solid solutions,” Acta Materialia vol. 61, pp. 4277-4288 2013. [↩]
  3. D. Chen, S. R. Bishop, and H. L. Tuller, “Praseodymium-cerium oxide thin film cathodes: Study of oxygen reduction reaction kinetics,” Journal of Electroceramics, vol. 28, no. 1, pp. 62–69, 2012. [↩]
  4. D. Chen, S. Bishop, and H. L. Tuller, “The chemical capacitance of praseodymium-cerium oxide thin films and relationship to nonstoichiometry,” Advanced Functional Materials, online, 2012. [↩]
  5. S. R. Bishop, T. S. Stefanik, and H. L. Tuller, “Electrical conductivity and defect equilibria of Pr0.1Ce0.9O2-δ,” Physical Chemistry Chemical Physics :  vol. 13, no. 21, pp. 10165–73, June 2011 [↩]

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