Self‐Regenerating Rh‐ and Pt‐Based Perovskite Catalysts for Automotive‐Emissions Control

Tanaka, Hiroyuki; Taniguchi, Masateru; Uenishi, Mari; Kajita, Nobuhiko; Tan, Isao; Nishihata, Yasuo; Mizuki, J.; Narita, Keiichi; Kimura, M.; Kaneko, Kimiyoshi

doi:10.1002/anie.200503938

Cited by 210 publications

(233 citation statements)

References 13 publications

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“…The system in La(Fe 1−x Rh x )O 3 favors a homogeneous mixing, in which Rh atoms tends to disperse in LaFeO 3 matrix and therefore less effective for the catalytic reactions than La(Fe 1−x Pd x )O 3 , as known in the experiment. 7) We now discuss relevance of SND for the realization of the regenerating catalytic function, which makes us possible to design new three-way catalysts. Before explaining the SND model, let us consider what happens if the catalysts are made from uniformly dispersed precious metals in the synthesis process and if SND does not occur.…”

Section: /10mentioning

confidence: 99%

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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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Section: /10mentioning

confidence: 99%

“…[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.…”

mentioning

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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“…11,15,23,[29][30][31][32][33][34][35][36][37] This concept is similar to that used in self-regenerating automotive emissions catalysts that were first developed by researchers at Daihatsu. 33,[35][36][37] So called "intelligent" automotive catalysts use perovskite (ABO 3 ) oxides (e.g. LaFeO 3 ) in which a catalytic metal, typically the noble metals Pd, Pt or Rh, is substituted for a small portion of the B-site cations.…”

mentioning

confidence: 94%

Polarization-Induced Hysteresis in CuCo-Doped Rare Earth Vanadates SOFC Anodes

Adijanto

Padmanabhan

Gorte

et al. 2012

J. Electrochem. Soc.

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The physical and electrochemical properties of strontium substituted cerium vandates in which a portion of the cerium cations have been substituted with transition metals (Ce 0.8 Sr 0.1 Cu 0.05 TM 0.05 VO 4−0.5x , TM = Ni or Co) were investigated and their suitability for use in solid oxide fuel cell (SOFC) anodes was assessed. Upon reduction at elevated temperature, Cu and Co or Cu and Ni were exsolved from the electronically conductive Ce 1−x Sr x VO 4 lattice to produce Cu-Ni and Cu-Co catalytic nanoparticles. The Ce 0.8 Sr 0.1 Cu 0.05 Co 0.05 VO 3 appears to have high activity and relatively high hydrocarbon tolerance, suggesting that intimate contact between the exsolved Cu and Co and that the majority of the Co nanoparticles must be at least partially coated with the Cu. The electrochemical performance when used in anodes operating on hydrogen has been characterized, and the results demonstrate the exsolution of both metals from the host lattice; but observed dynamic changes in the structure of the resulting metal nanoparticles as a function of SOFC operating conditions complicate their use in SOFC anodes.

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“…[1][2][3] Different synthesis methods have been so far employed to synthesize Pt nanostructures with various morphologies. Electrospinning was for instance successfully carried out for the synthesis of Pt nanowires.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of a 3D network of Pt nanowires by atomic layer deposition on a carbonaceous template

et al. 2014

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The formation of a 3D network composed of free standing and interconnected Pt nanowires is achieved by a two-step method, consisting of conformal deposition of Pt by atomic layer deposition (ALD) on a forest of carbon nanotubes and subsequent removal of the carbonaceous template. Detailed characterization of this novel 3D nanostructure was carried out by transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). These characterizations showed that this pure 3D nanostructure of platinum is self-supported and offers an enhancement of the electrochemically active surface area by a factor of 50.

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Self‐Regenerating Rh‐ and Pt‐Based Perovskite Catalysts for Automotive‐Emissions Control

Cited by 210 publications

References 13 publications

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

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

Polarization-Induced Hysteresis in CuCo-Doped Rare Earth Vanadates SOFC Anodes

Synthesis of a 3D network of Pt nanowires by atomic layer deposition on a carbonaceous template

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