Cu-doped Zr-Ce-Pr-O mixed oxide phases with high Oxygen Storage Capacity (OSC)

Tadatoshi Murota, Kosuke Sogawa, Shinya Otsuka-Yao-Matsuo, Takahisa Omata

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Oxide materials with high oxygen storage capacity (OSC) at low temperatures, possessing high thermal stability at high temperatures are indispensable for advanced automotive exhaust catalyst. A candidate for the high efficient OSC materials must lie in the composition of (Zr 2/8Ce x/8Pr (6-X)/8)O 2-y. (x = 0∼6), because the small amount of Ce addition stabilizes a single phase of λ(Zr 0.25Pr 0.75) O 2-y, with wide oxygen nonstoichiometry. In addition, noble catalytic metal, e.g., copper must be investigated instead of platinum. In the present work, the (Zr 2/8Ce x/8Pr (6-x)/0.8)O 2-y compositions (x = 0∼6) with the addition of Cu have been investigated for the phase relationship and OSC behavior. The samples were first oxidized at 1473 K in air, reduced in H 2 at 1373 K, and then oxidized again at 973 K in air, The oxide samples obtained in each situation were subjected to XRD, OSC analysis and TPD oxygen gas analysis by means of TG/DTA in the Ar + 5% H 2. When oxidized at 1473 K in air, the two-phases region between the λ-and C-phases, observed for (Zr 2.8Ce x-8Pr (6-x)/8)O 2-y, disappeared and a pyrochlore-like phase appeared with the addition of Cu. That is, the addition of Cu led to the mutual solid solution of λ-and C-phases. When the samples (Zr 2.8Ce x/8Z8Pr (6-x)/8)Cu 0.5/8O 2-y ( x < 3) were reduced at 1373 K in H 2. C-rare earthslike phase appeared on (Zr 2/8Ce x/8Pr (6-x)/8)Cu 0.5/8O 2-y ( x < 3). With increasing the Ce content, the lattice parameter of the CaF 2 unit varied continuously to those of λ- and C-phases. For the samples (Zr 2/8Ce x/8Pr (6-x)/8)Cu 0.5/8 O 2-y (x = 0∼6), the oxygen storage capacity was greatly improved at low temperatures as 573 K, probably due to the oxygen defect of pyrochlore-like phase.

Original languageEnglish
Pages (from-to)268-274
Number of pages7
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume73
Issue number4
DOIs
Publication statusPublished - 2009 Apr
Externally publishedYes

Keywords

  • Exhaust catalyst
  • Mixed oxide
  • Oxygen nonstoichiometr
  • Oxygen storage capacity
  • Thermal stability

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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