Reduction of CeO2 in composites with transition metal complex oxides under hydrogen containing atmosphere and its correlation with catalytic activity

Elena Yu Konysheva

Research output: Journal PublicationArticlepeer-review

3 Citations (Scopus)

Abstract

Reduction behavior of pure and doped CeO2, the multi-phase La0.6Sr0.4CoO3·xCeO2, La0.8Sr0.2MnO3·xCeO2, and La0.95Ni0.6Fe0.4O3·xCeO2 composites, was studied under hydrogen containing atmosphere to address issues related to the improvement of electrochemical and catalytic performance of electrodes in fuel cells. The enhanced reduction of cerium oxide was observed initially at 800°C in all composites in spite of the presence of highly reducible transition metal cations that could lead to the increase in surface concentration of oxygen vacancies and generation of the electron enriched surface. Due to continuous reduction of cerium oxide in La0.6Sr0.4CoO3·x-CeO2 and La0.8Sr0.2MnO3·xCeO2 (up to 10 h) composites the redox activity of the Ce4+/Ce3+ pair could be suppressed and additional measures are required for reversible spontaneous regeneration of Ce4+. After 3 h exposure to H2-Ar at 800°C the reduction of cerium oxides and perovskite phases in La0.95Ni0.6Fe0.4O3·xCeO2 composites was diminished. The extent of cerium oxide involvement in the reduction process varies with time, and depends on its initial deviation from oxygen stoichiometry (that results in the larger lattice parameter and the longer pathway for O2- transport through the fluorite lattice), chemical origin of transition metal cations in the perovskite, and phase diversity in multi-phase composites.

Original languageEnglish
Pages (from-to)249-261
Number of pages13
JournalFrontiers of Chemical Science and Engineering
Volume7
Issue number3
DOIs
Publication statusPublished - Sep 2013
Externally publishedYes

Keywords

  • catalyst under hydrogen containing atmosphere
  • composites
  • perovskites
  • reduction of cerium oxide

ASJC Scopus subject areas

  • Chemical Engineering (all)

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