A thermochemical study of ceria: Exploiting an old material for new modes of energy conversion and CO2 mitigation

William C. Chueh, Sossina M. Haile

Research output: Contribution to journalArticle

312 Scopus citations

Abstract

We present a comprehensive thermodynamic and kinetic analysis of the suitability of cerium oxide (ceria) for thermochemical fuel production. Both portions of the two-step cycle, (i) oxygen release from the oxide at 1773 and 1873K under inert atmosphere, and (ii) hydrogen release upon hydrolysis at 1073 K, are examined theoretically as well as experimentally. We observe gravimetric fuel productivity that is in quantitative agreement with equilibrium, thermogravimetric studies of ceria. Despite the non-stoichiometric nature of the redox cycle, in which only a portion of the cerium atoms change their oxidation state, the fuel productivity of 8.5-11.8 ml of H2 per gram of ceria is competitive with that of other solid-state thermochemical cycles currently under investigation. The fuel production rate, which is also highly attractive, at a rate of 4.6-6.2 ml of H2 per minute per gram of ceria, is found to be limited by a surface-reaction step rather than by ambipolar bulk diffusion of oxygen through the solid ceria. An evaluation of the thermodynamic efficiency of the ceria-based thermochemical cycle suggests that, even in the absence of heat recovery, solar-to-fuel conversion efficiencies of 16 to 19 per cent can be achieved, assuming a suitable method for obtaining an inert atmosphere for the oxygen release step.

Original languageEnglish (US)
Pages (from-to)3269-3294
Number of pages26
JournalPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume368
Issue number1923
DOIs
StatePublished - Jul 28 2010

Keywords

  • Cerium oxide
  • Hydrogen
  • Syngas
  • Thermochemical cycles
  • Water splitting

ASJC Scopus subject areas

  • Mathematics(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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