LaFePdO3 perovskite automotive catalyst having a self-regenerative function

Tanaka, Hiroyuki; Tan, Isao; Uenishi, Mari; Taniguchi, Masateru; Kimura, M.; Nishihata, Yasuo; Мizuki, J.

doi:10.1016/j.jallcom.2004.12.138

Cited by 60 publications

(61 citation statements)

References 26 publications

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“…Moreover, the activity of catalysts is significantly influenced by their chemical nature [7,[24][25][26]. Giebeler.L [10] and Tanaka [11,12] found that most of the desorbed oxygen was caused when Pd was as Pd 3? or Pd 4? state in perovskites.…”

Section: Tem and Semmentioning

confidence: 99%

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LaCo1−x Pd x O3 Perovskite-Type Oxides: Synthesis, Characterization and Simultaneous Removal of NO x and Diesel Soot

2009

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A series of naometric perovskite catalysts LaCo 1-x Pd x O 3 (x = 0, 0.01, 0.03) were prepared via a solution combustion synthesis route using metal nitrates as oxidizers and urea as fuel. It is essential to add a certain amount of ammonia aqueous solution to Pd 2? ions solution in the catalyst preparation process. Homogeneous nanoparticles LaCo 1-x Pd x O 3 catalysts with the sizes in the range of 68-122 nm were obtained and characterized by using of XRD, BET, H 2 -TPR, XPS, SEM and TEM. Pd was successfully introduced into the LaCoO 3 perovskite lattices. Further information was obtained by using XPS upon the LaCo 0.97 Pd 0.03 O 3 (with NH 4 OH) sample after H 2 -TPR. The results revealed that surface Pd was reduced to the metallic state at the end of the first step in the H 2 -TPR experiment, and some surface Co could be reduced to metallic Co simultaneously. The catalytic properties were investigated for simultaneous NO x -soot removal reaction. The performance of LaCo 1-x Pd x O 3 catalysts were greatly improved by the partial substitution of Pd. The maximum NO conversion into N 2 and the ignition temperature of soot are 32.8% and 265°C, respectively.

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Section: Tem and Semmentioning

confidence: 99%

“…LaMnO 3 perovskites supported noble metal (Pt, Pd, Rh) catalysts prepared by the citrate method are used for the total oxidation of methane and CH 4 oxidation activity is enhanced [10]. Tanaka [11] prepared LaFe 0.95 Pd 0.05 O 3 perovskite catalyst by the alkoxide method. ''The intelligent catalyst'' has a self-regenerative function.…”

Section: Introductionmentioning

confidence: 99%

LaCo1−x Pd x O3 Perovskite-Type Oxides: Synthesis, Characterization and Simultaneous Removal of NO x and Diesel Soot

2009

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“…[1][2][3][4][5][6][7][8][9][10][11] In a conventional catalyst made of fine precious-metal particles supported on a solid like an almina, agglomeration of the metal particles is inevitable because of high temperature conditions in the redox environment. This is the very reason for deterioration of automotive three-way catalysts.…”

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confidence: 99%

Generation of Nano-Catalyst Particles by Spinodal Nano-Decomposition in Perovskite

Kizaki

Kusakabe

Nogami

et al. 2008

Appl. Phys. Express

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A new mechanism of nano-catalyst generation based on the spinodal nano-decomposition in self-regenerating perovskite catalysts for automotive-emissions control is proposed. To demonstrate existence of the spinodal nano-decomposition in real perovskite catalysts, we performed first-principles calculations to evaluate the free energy of La(Fe 1−x Pd x )O 3 and La(Fe 1−x Rh x )O 3 . The result indicates appearance of a spinodal region in the phase diagram of each material. Formation of nano-catalyst particles in the perovskite host matrix is crucial for the self-regeneration of perovskite catalyst. Based on the spinodal nano-decomposition model, possible materials are designed for new three-way catalyst with no contents of precious metal.Self-regenerating Pd-, Rh-, and Pt-doped perovskite catalysts for automotive-emissions control are attracting much interest due to their unique functionalities. [1][2][3][4][5][6][7][8][9][10][11] In a conventional catalyst made of fine precious-metal particles supported on a solid like an almina, agglomeration of the metal particles is inevitable because of high temperature conditions in the redox environment. This is the very reason for deterioration of automotive three-way catalysts. In the self-regenerating perovskite catalysts, interestingly, the deterioration is strongly suppressed. Therefore, consumption of the precious metal is greatly reduced, providing a highly efficient solution for supply problems. The reason for non-deterioration is thought to be reformation of a precious-metal doped perovskite lattice in the NO x -reduction environment from segregated nano-particles of precious-metal created in the CO-and C x H-oxidation environment. In this regeneration model, precious-metal atoms are assumed to move into and out of the perovskite host matrixes. Growth of precious-metal grains is suppressed due to this repeated motion of precious metal atoms between a solid solution and metallic nano-particles during three-way catalytic reactions.In some doped perovskite structures, it is known that diffusion of oxygen happens rather frequently. At the same time, we may expect motion of metal atoms via a process exchanging metallic atoms. The process would be enhanced, if oxygen vacancies are created in the perovskite host crystal. This scenario might support the above model of self-regenerating perovskite catalysts. For realization of high efficiency in the three-way catalytic functions with * E-mail address: hkizaki@aquarius.mp.es.osaka-u.ac.jp 1/10Submitted to Applied Physics Express no deterioration, however, we should consider another model of the self-regenerating catalyst. The new model should explain some mysteries known experimentally in the perovskite catalyst. The self-regeneration can happen, only when the host perovskite lattice structure maintains its essential structure. We need to know why the redox reaction keeps its cycle in a redox environment changing in a frequency of about a few hertz (1 ∼ 4 Hz). Thus we need to understand motion of precious metal atoms in a rat...

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“…[8][9][10] Since the addition of precious metal particles on the surface of the mixed oxides was shown to be critical in lowering the reduction temperature, the amount of such precious metals employed in the automotive catalysts has increased drastically over the last decade, reflecting the growing strength of worldwide emission regulations. [11,12] Consequently, it is of great urgency to develop new materials that can reduce or eliminate the amount of precious metals in automotive exhaust catalysts. In terms of the physical stability for the practical application of CZB as an automotive exhaust catalyst, it was reasoned that a supported catalyst, in which the CZB phase is dispersed over a stable inert support, would improve the redox activity and thermal stability of the catalyst.…”

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confidence: 99%

Significant Low‐Temperature Redox Activity of Ce_0.64Zr_0.16Bi_0.20O_1.90 Supported on γ‐Al₂O₃

Imanaka¹,

Masui²,

Koyabu³

et al. 2007

Advanced Materials

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LaFePdO3 perovskite automotive catalyst having a self-regenerative function

Cited by 60 publications

References 26 publications

LaCo1−x Pd x O3 Perovskite-Type Oxides: Synthesis, Characterization and Simultaneous Removal of NO x and Diesel Soot

LaCo1−x Pd x O3 Perovskite-Type Oxides: Synthesis, Characterization and Simultaneous Removal of NO x and Diesel Soot

Generation of Nano-Catalyst Particles by Spinodal Nano-Decomposition in Perovskite

Significant Low‐Temperature Redox Activity of Ce_0.64Zr_0.16Bi_0.20O_1.90 Supported on γ‐Al₂O₃

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LaFePdO3 perovskite automotive catalyst having a self-regenerative function

Cited by 60 publications

References 26 publications

LaCo1−x Pd x O3 Perovskite-Type Oxides: Synthesis, Characterization and Simultaneous Removal of NO x and Diesel Soot

LaCo1−x Pd x O3 Perovskite-Type Oxides: Synthesis, Characterization and Simultaneous Removal of NO x and Diesel Soot

Generation of Nano-Catalyst Particles by Spinodal Nano-Decomposition in Perovskite

Significant Low‐Temperature Redox Activity of Ce0.64Zr0.16Bi0.20O1.90 Supported on γ‐Al2O3

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Significant Low‐Temperature Redox Activity of Ce_0.64Zr_0.16Bi_0.20O_1.90 Supported on γ‐Al₂O₃