| Project/Area Number |
15350090
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional materials chemistry
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| Research Institution | Japan Atomic Energy Agency |
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Principal Investigator |
NISHIHATA Yasuo Japan Atomic Energy Agency, Senior Scientist, 量子ビーム応用研究部門, 副主任研究員 (90218181)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUKI Jun'ichiro Japan Atomic Energy Agency, Supreme Researcher, 量子ビーム応用研究部門, 上級研究主席 (90354977)
TANAKA Hirohisa Daihatsu Motor Co. Ltd., Principal Scientist, 主査
UENISHI Mari Daihatsu Motor Co. Ltd., Senior Researcher, 係長
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥8,100,000 (Direct Cost: ¥8,100,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥5,900,000 (Direct Cost: ¥5,900,000)
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| Keywords | catalysis / automotive catalyst / self-regeneration / synchrotron radiation / XAFS / x-ray anomalous scattering / perovskite / precious metals / 触媒 / 自動車排ガス浄化 / X線異常分散 / 時分割 / ガソリンエンジン / 排ガス / 時分割XAFS |
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| Research Abstract |
Palladium-containing perovskite catalysts (the intelligent catalyst) retain the high metal dispersion due to structural responses to the inherent redox fluctuation in exhaust-gas composition with gasoline engines. Palladium occupied the B-site of the perovskite structure in the oxidative atmosphere, and segregated out to form small metallic particles in the reductive atmosphere. The reversible movement of palladium suppressed the agglomeration and growth of the metal particles, maintaining the large total surface area of the precious metals and high catalytic activity. The great reduction of palladium loading was achieved with the self-regeneration of the precious metals. On the other hand, iron plays an important role to stabilize the perovskite structure.
The intelligent catalyst exhibited the superior start-up activity. In the reductive atmosphere, Pd^0 species was partially segregated out onto the catalyst surface even at temperatures as low as 100℃. In the successive oxidizing atmosphere, the segregated Pd^0 species was re-oxidized into Pd^<2+> at 200-300℃. Palladium occupied again the B-site of the perovskite structure above about 400℃. The behavior of palladium depended on temperature. It was also found that the local structure change around palladium occurred faster than the fluctuation of redox atmosphere of the exhaust-gas (1-4Hz) by using time-resolved XAFS (DXAFS) technique with the time resolution of 10msec.
In this study, we succeeded in realizing the intelligent catalysts for rhodium and platinum, as well as palladium. The intelligent catalyst is expected to solve the issue of supply and demand for precious metals in the world, and to become the global standard of the catalyst technology.
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