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Journal Articles

Towards optimizing the performance of self-regenerating Pt-based perovskite catalysts

Jarrige, I.*; Ishii, Kenji; Matsumura, Daiju; Nishihata, Yasuo; Yoshida, Masahiro*; Kishi, Hirofumi*; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*; Kasai, Hideaki*; et al.

ACS Catalysis, 5(2), p.1112 - 1118, 2015/02

 Times Cited Count:14 Percentile:43.47(Chemistry, Physical)

Journal Articles

A Theoretical study of the reactivity of Cu$$_{2}$$O(111) surfaces; The Case of NO dissociation

Kishi, Hirofumi*; Padama, A. A. B.*; Arevalo, R. L.*; Moreno, J. L. V.*; Kasai, Hideaki*; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*; Nishihata, Yasuo

Journal of Physics; Condensed Matter, 24(26), p.262001_1 - 262001_5, 2012/07

 Times Cited Count:9 Percentile:41.97(Physics, Condensed Matter)

no abstracts in English

Journal Articles

NO dissociation on Cu(111) and Cu$$_{2}$$O(111) surfaces; A Density functional theory based study

Padama, A. A. B.*; Kishi, Hirofumi*; Arevalo, R. L.*; Moreno, J. L. V.*; Kasai, Hideaki*; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*; Nishihata, Yasuo

Journal of Physics; Condensed Matter, 24(17), p.175005_1 - 175005_6, 2012/05

 Times Cited Count:34 Percentile:79.58(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Dynamic structural change in Pd-perovskite automotive catalyst studied by time-resolved dispersive X-ray absorption fine structure

Matsumura, Daiju; Nishihata, Yasuo; Mizuki, Junichiro; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*

Journal of Applied Physics, 107(12), p.124319_1 - 124319_5, 2010/06

 Times Cited Count:17 Percentile:59.84(Physics, Applied)

The structural transformation of a Pd-perovskite automotive catalyst, LaFe$$_{0.9}$$Pd$$_{0.1}$$O$$_{3}$$, which has a high catalytic activity during aging, was studied by in situ time-resolved dispersive X-ray absorption fine structure spectroscopy at 473-773 K. An Al$$_{2}$$O$$_{3}$$-based conventional catalyst was also studied. In a reductive atmosphere, both catalysts showed similar temperature dependences of structural transformation from an oxide to a metal. However, different temperature dependence was observed in an oxidative atmosphere. A faster response in the structural change was observed in the Pd-perovskite catalyst than in the Pd/Al$$_{2}$$O$$_{3}$$ catalyst. It was revealed that Pd-perovskite shows a considerably fast structural change to the oxidized state via the movement of Pd atoms into the perovskite crystal, in comparison with Pd/Al$$_{2}$$O$$_{3}$$ showing two-step structural change for making PdO.

Journal Articles

Dynamic structural change of Pd particles on LaFeO$$_{3}$$ under redox atmosphere and CO/NO catalytic reaction studied by dispersive XAFS

Matsumura, Daiju; Okajima, Yuka; Nishihata, Yasuo; Mizuki, Junichiro; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*

Journal of Physics; Conference Series, 190, p.012154_1 - 012154_6, 2009/11

 Times Cited Count:10 Percentile:91.83

Pd/LaFeO$$_{3}$$ is known to keep the metal particle size small even after the long time redox processes because Pd atoms make complex oxide with LaFeO$$_{3}$$ perovskite-type crystal under the oxidative atmosphere. We observed the local structure of Pd atoms by dispersive optics from the viewpoint of dynamical structure change of Pd during metal-oxide change and CO-NO catalytic reaction. It was recognized that, under the reductive atmosphere, Pd atoms show similar speed of movement from oxide to metal state both on LaFeO$$_{3}$$ and Al$$_{2}$$O$$_{3}$$. However, under the oxidative atmosphere, Pd atoms on LaFeO$$_{3}$$ show faster movement from metal to oxide state with single reaction step than those on Al$$_{2}$$O$$_{3}$$ with two-step oxidation. In addition, many differences in structure and shape between Pd particles on LaFeO$$_{3}$$ and Al$$_{2}$$O$$_{3}$$ are observed.

Journal Articles

Time evolution of palladium structure change with redox fluctuations in a LaFePdO$$_{3}$$ perovskite automotive catalyst by high-speed analysis with in situ DXAFS

Uenishi, Mari*; Tanaka, Hirohisa*; Taniguchi, Masashi*; Tan, Isao*; Nishihata, Yasuo; Mizuki, Junichiro; Kobayashi, Tetsuhiko*

Catalysis Communications, 9(2), p.311 - 314, 2008/02

 Times Cited Count:32 Percentile:63.72(Chemistry, Physical)

In the LaFePdO$$_{3}$$ perovskite catalyst, redox fluctuations of the exhaust gas suppress the growth of particles of precious metal by causing Pd to move in and out of the perovskite crystal. To observe the real movements of Pd directly, the time evolution of local structure around Pd by redox fluctuations was investigated by in situ energy-dispersive X-ray absorption fine-structure (DXAFS) analysis with a 10ms resolution. We proved that the change in structure of Pd is sufficiently fast to respond to the control frequency (1-4Hz) of an actual gasoline engine and that the Pd particles that segregate out are extremely fine.

Journal Articles

Self-regenerating Rh- and Pt-based perovskite catalysts for automotive-emissions control

Tanaka, Hirohisa*; Taniguchi, Masashi*; Uenishi, Mari*; Kajita, Nobuhiko*; Tan, Isao*; Nishihata, Yasuo; Mizuki, Junichiro; Narita, Keiichi*; Kimura, Mareo*; Kaneko, Kimiyoshi*

Angewandte Chemie; International Edition, 45(36), p.5998 - 6002, 2006/09

 Times Cited Count:142 Percentile:93.27(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

The Intelligent catalyst having the self-regenerative function of Pd, Rh and Pt for automotive emissions control

Tanaka, Hirohisa*; Uenishi, Mari*; Taniguchi, Masashi*; Tan, Isao*; Narita, Keiichi*; Kimura, Mareo*; Kaneko, Kimiyoshi*; Nishihata, Yasuo; Mizuki, Junichiro

Catalysis Today, 117(1-3), p.321 - 328, 2006/09

 Times Cited Count:178 Percentile:98.02(Chemistry, Applied)

no abstracts in English

Journal Articles

The Intelligent catalyst; Pd-perovskite having the self-regenerative function in a wide temperature range

Tanaka, Hirohisa*; Tan, Isao*; Uenishi, Mari*; Taniguchi, Masashi*; Nishihata, Yasuo; Mizuki, Junichiro

Key Engineering Materials, 317-318, p.827 - 832, 2006/08

no abstracts in English

Journal Articles

The Self-regenerative "intelligent" catalyst for automotive emissions control

Tan, Isao*; Taniguchi, Masashi*; Tanaka, Hirohisa*; Uenishi, Mari*; Kajita, Nobuhiko*; Nishihata, Yasuo; Mizuki, Junichiro; Niihara, Koichi*

Key Engineering Materials, 317-318, p.833 - 836, 2006/08

no abstracts in English

Journal Articles

LaFePdO$$_{3}$$ perovskite automotive catalyst having a self-regenerative function

Tanaka, Hirohisa*; Tan, Isao*; Uenishi, Mari*; Taniguchi, Masashi*; Kimura, Mareo*; Nishihata, Yasuo; Mizuki, Junichiro

Journal of Alloys and Compounds, 408-412, p.1071 - 1077, 2006/02

 Times Cited Count:49 Percentile:90.02(Chemistry, Physical)

no abstracts in English

Journal Articles

Development of a Rh-intelligent catalyst

Naito, Kazuya*; Tanaka, Hirohisa*; Taniguchi, Masashi*; Uenishi, Mari*; Tan, Isao*; Kajita, Nobuhiko*; Takahashi, Ichiro*; Suzuki, Hiromasa*; Narita, Keiichi*; Hirai, Akimasa*; et al.

SAE 2006 World Congress & Exhibition Technical Papers, 8 Pages, 2006/00

no abstracts in English

Journal Articles

Self-regeneration of a Pd-perovskite catalyst for automotive emissions control

Nishihata, Yasuo; Mizuki, Junichiro; Akao, Takahiro; Tanaka, Hirohisa*; Uenishi, Mari*; Kimura, Mareo*; Okamoto, Tokuhiko*; Hamada, Noriaki*

Nature, 418(6894), p.164 - 167, 2002/07

 Times Cited Count:820 Percentile:99.81(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

An Intelligent catalyst

Tanaka, Hirohisa*; Uenishi, Mari*; Tan, Isao*; Kimura, Mareo*; Mizuki, Junichiro; Nishihata, Yasuo

SAE 2001 World Congress Paper; Advanced Catalytic Converters and Substrates for Gasoline Emission Systems (SP1573), p.1 - 8, 2001/00

The catalyst of the crystalline ceramics known as a perovskite-type oxide was designed and controlled at the atomic level in order to create a new function for self-regeneration of precious metals in a usage ambience without auxiliary treatment.

Oral presentation

Anormalous changes in perovskite-type automobile catalyst observed by using dispersive XAFS

Matsumura, Daiju; Nishihata, Yasuo; Mizuki, Junichiro; Okajima, Yuka; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*

no journal, , 

It has been proved that the amount of rare metal in automobile catalyst can be reduced drastically by using Perovskite-type automobile catalyst. In this study, we observed that the chemical reaction of rare matel induced Perovskite-type automobile catalyst by dispersive XAFS system. The dispersive XAFS system supplies wide energy range of X-ray used in XAFS spectrum and has an advantage of time resolved observation comparing with conventional XAFS system. Pd induced Perovskite-type catalyst was measured in in-situ oxidation and reduction conditions at 50 ms time scale. It is revealed that the Perovskite-type catalyst shows fast oxidation reaction even at low temperature, while normal alumina-type catalyst shows slow reaction. This small reaction energy of the Perovskite-type catalyst at the oxidation is considerd as the origin of preventing of the small particle while long-time reaction because the rare metal can be induced in the Perovskite crystal easily.

Oral presentation

Catalytic properties of perovskite-type automotive catalysts studied by dispersive XAFS

Matsumura, Daiju; Nishihata, Yasuo; Mizuki, Junichiro; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*

no journal, , 

In-situ and real-time structural transformations of perovskite-type automotive catalysts having a high catalytic activity during aging were observed by dispersive XAFS method. Alumina-based conventional catalysts were also observed for reference. The experiments were operated at the beamline of SPring-8 BL14B1. Just after dosing by oxygen or hydrogen, continuous XAFS spectra were measured at 20-50 Hz in order to reveal the local structural transformation of precious metals. For the Pd-perovskite catalyst, the slower response of structural transformation was observed than the alumina-based catalyst under the oxygen atmosphere. Similar results were observed in Pt-based catalyst. On the other hand, there were no clear differences between the perovskite-type and alumina-based catalyst of Rh.

Oral presentation

Dynamic structural change of Pd-perovskite automotive catalyst studied by dispersive XAFS at SPring-8 BL14B1

Matsumura, Daiju; Okajima, Yuka; Nishihata, Yasuo; Mizuki, Junichiro; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*

no journal, , 

Pd/LaFeO$$_{3}$$ automotive catalyst makes the solid solution under the oxidative atmosphere and the mechanism prevents sintering of particles. We observed dynamic structural change of the catalyst by dispersive XAFS system at the rate of 20-50 Hz. It is revealted that the catalyst shows faster structure change under the oxidative atmosphere than normal particles. The fast creation of solid solution is the key of preventing agglomeration of particles.

Oral presentation

Dynamic structure of Pd metal particles during CO/NO catalytic reaction

Matsumura, Daiju; Okajima, Yuka; Nishihata, Yasuo; Mizuki, Junichiro; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*

no journal, , 

Dynamic structure changes of Pd metal particles on LaFeO$$_{3}$$ and Al$$_{2}$$O$$_{3}$$ were observed by dispersive XAFS optics during successive gas change of CO/NO. Observation rate of 0.2 Hz for dispersive XAFS enabled us to study precise structure of Pd metal particles under oxidation-reduction, expansion-contraction and sintering-dispersion transformations during gas change. Especially, it was revealed that the Pd particles on Al$$_{2}$$O$$_{3}$$ show faster reaction for expansion of lattice under CO atmosphere and inner oxidation under NO atmosphere than those on LaFeO$$_{3}$$. High relative precision study showed many undetected changes of Pd metal particles.

Oral presentation

In situ and real-time XAFS study for the structure anad shape of Pd metal particles under CO/NO atmosphere

Matsumura, Daiju; Okajima, Yuka; Nishihata, Yasuo; Mizuki, Junichiro; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*

no journal, , 

Dynamic structure changes of Pd metal particles on LaFeO$$_{3}$$ and Al$$_{2}$$O$$_{3}$$ were observed by dispersive XAFS optics during successive gas change of CO/NO. Observation rate of 0.2 Hz for dispersive XAFS enabled us to study precise structure of Pd metal particles under oxidation-reduction, expansion-contraction and sintering-dispersion transformations during gas change. Especially, it was revealed that the Pd particles on Al$$_{2}$$O$$_{3}$$ show faster reaction for expansion of lattice under CO atmosphere and inner oxidation under NO atmosphere than those on LaFeO$$_{3}$$. Depending on the interaction between metal particle and support, many surface adsorption structure on Pd metal particles were influenced.

Oral presentation

Self-regeneration of perovskite-based catalyst, 1; Crystal structure

Taniguchi, Masashi*; Kan, C. Y.*; Uenishi, Mari*; Tanaka, Hirohisa*; Matsumura, Daiju; Nishihata, Yasuo; Mizuki, Junichiro; Uozumi, Akifumi*; Hamada, Ikutaro*; Morikawa, Yoshitada*

no journal, , 

no abstracts in English

23 (Records 1-20 displayed on this page)