TWC Performance of Honeycomb Catalysts Coated with Pd-Supported 10Al2O3 · 2B2O3 and Its Cation-Substituted Compounds

Nagao, Yuki; Nakahara, Yujiro; Sato, Takahiro; Nakano, Shuji; Machida, Masato

doi:10.1007/s40825-016-0037-z

Cited by 8 publications

(2 citation statements)

References 36 publications

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“…Although the Al 2 O 3 -based support, which contains CeO 2 as an oxygen storage component, has been widely used for Pd, it cannot be used for Rh. Serious deactivation of Rh/Al 2 O 3 occurs when thermal aging is performed at ≥600 °C in the presence of O 2 due to undesired interactions between the Rh oxide and Al 2 O 3 . − Rh is therefore supported on ZrO 2 -based oxides, which exhibit negligible solid reactivity to the Rh oxide. , In modern commercial TWCs, supported Rh and Pd catalysts are coated separately in the top and bottom layers, respectively, on a honeycomb substrate to prevent undesired interactions between Rh and Al 2 O 3 . − …”

Section: Introductionmentioning

confidence: 99%

Thermostable Rh Metal Nanoparticles Formed on Al₂O₃ by High-Temperature H₂ Reduction and Its Impact on Three-Way Catalysis

Machida

Uchida²,

Ishikawa³

et al. 2019

J. Phys. Chem. C

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The influence of high-temperature H2 reduction treatment on Rh and Pd catalysts supported on Al2O3 was studied in relation to thermal aging in air. After air-aging at ≥900 °C, the Rh/Al2O3 catalyst was more strongly deactivated compared with the Pd/Al2O3 catalyst. As has been widely recognized, the solid-state reactions between Rh oxide and Al2O3 decreased the active surface area and stabilized inactive Rh3+ species. The activity was restored by the postreduction treatment with 20% H2/He at 200 °C, whereas a striking enhancement of activity was achieved by the reduction at 800–1100 °C, where substantial deactivation occurred for Pd/Al2O3. A mechanistic interpretation is proposed based on local structural characterization, which explains these contrasting thermal behaviors. The high-temperature reduction treatment produced active and thermostable Rh metal nanoparticles, which were highly dispersed on Al2O3. The observed dispersion (as high as ∼20% after reduction at 1000 °C) is among the highest for supported Rh catalysts reported in the literature. This is in complete contrast to the rapid sintering of Pd and other precious metals (Ru and Pt) into large metal agglomerates greater than 50 nm. Because the thermal behavior observed for Rh/ZrO2 under both oxidizing and reducing atmospheres was similar to that of Pd/Al2O3, the stability of metal nanoparticles depended not only on metal species but also on the interactions with support materials. An important implication of this study is that Al2O3 is a very efficient support for anchoring Rh metal nanoparticles via interfacial Rh–O–Al bonding under strong reducing conditions, in contrast to the well-known incompatibility with Rh oxide under oxidizing conditions.

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Section: Introductionmentioning

confidence: 99%

Thermostable Rh Metal Nanoparticles Formed on Al₂O₃ by High-Temperature H₂ Reduction and Its Impact on Three-Way Catalysis

Machida

Uchida²,

Ishikawa³

et al. 2019

J. Phys. Chem. C

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“…The catalyst support plays a very important role in improving the thermal stability of the catalyst material. − Usually, TWCs consist of platinum-group-metal (PGM) species, such as Pd, Rh, and Pt species, loaded on Al 2 O 3 and/or CeO 2 –ZrO 2 supports. If the PGM species are extremely aggregated by the high temperature, the catalytic activity dramatically decreases due to decreases in the number of effective active sites.…”

Section: Introductionmentioning

confidence: 99%

Pd/SrFe_1–xTi_xO_3−δ as Environmental Catalyst: Purification of Automotive Exhaust Gases

Beppu

Demizu

Hosokawa

et al. 2018

ACS Appl. Mater. Interfaces

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Environmental catalysts are required to operate highly efficiently under severe conditions in which they are exposed to reductive and oxidative atmospheres at high temperatures. This study demonstrates that SrFeTi O-supported Pd catalysts exhibit high catalytic activities for NO reduction with CH and CO in the presence of O, which is a model reaction for the purification of automotive exhaust gases. Catalytic activity is enhanced with increasing Ti content, and the highest activity is observed for Pd/SrFeTiO among the examined catalysts. The state of the loaded Pd species can be controlled by the Fe/(Fe + Ti) ratio in SrFeTi O, and highly active PdO nanoparticles are properly anchored on SrFeTiO. The Ti-rich Pd/SrFeTiO shows significantly higher catalytic activity and is more thermally stable than the conventional Pd/AlO, which has a high surface area. Since Fe-rich SrFeTi O has the high oxygen storage capacity, its response capabilities to atmospheric fluctuations were evaluated by changing the oxygen concentration during NO reduction. As a result, Fe-rich Pd/SrFeTiO retains its high NO-reduction activity for longer times even under oxidative conditions, when compared to SrFeO or Ti-rich Pd/SrFeTi O. The oxygen storage properties of Pd/SrFeTiO allow it to effectively act as an oxygen buffer for NO reduction. These properties ensure that the SrFeTi O support, with both high thermal stability and oxygen storage capacity, is a very useful environmental-catalyst material.

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Low‐Temperature CO Oxidation by the Pt/CeO₂ Based Catalysts

Stadnichenko,

Slavinskaya,

Stonkus

et al. 2024

ChemCatChem

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This review analyzes the literature data and the results of studies of the Pt/CeO2‐based catalysts that are capable of providing the low‐temperature CO oxidation (LTO CO). The review summarizes the catalytic characteristics and the main properties of Pt/CeO2‐based catalysts necessary for the low‐temperature oxidation at T < 50 oC. Analysis of the literature data on the use of physical methods of investigation and their correlation with the activity of Pt/CeO2 catalysts allowed us to conclude that the main active forms of platinum are small metallic clusters, single atoms Pt2+‐SA and oxide clusters PtOx interacting with ceria nanoparticles. It has been established that the most active forms are PtOx clusters, which provide a high reaction rate in the temperature range from ‐50 to +50 °C. Forms of ionic Pt2+ with different coordination with oxygen ensure the activity of catalysts starting at temperatures above 100 °C. Finally, small metallic clusters occupy an intermediate position, providing activity above 0 °C, but their instability and gradual transition to the oxidized state Pt2+/PtOx are noted. At the conclusion of the review, the results of mathematical modeling demonstrate the correct kinetics description of the low‐temperature CO oxidation based on the Mars‐van Krevelen and associative mechanisms.

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TWC Performance of Honeycomb Catalysts Coated with Pd-Supported 10Al2O3 · 2B2O3 and Its Cation-Substituted Compounds

Cited by 8 publications

References 36 publications

Thermostable Rh Metal Nanoparticles Formed on Al₂O₃ by High-Temperature H₂ Reduction and Its Impact on Three-Way Catalysis

Thermostable Rh Metal Nanoparticles Formed on Al₂O₃ by High-Temperature H₂ Reduction and Its Impact on Three-Way Catalysis

Pd/SrFe_1–xTi_xO_3−δ as Environmental Catalyst: Purification of Automotive Exhaust Gases

Low‐Temperature CO Oxidation by the Pt/CeO₂ Based Catalysts

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TWC Performance of Honeycomb Catalysts Coated with Pd-Supported 10Al2O3 · 2B2O3 and Its Cation-Substituted Compounds

Cited by 8 publications

References 36 publications

Thermostable Rh Metal Nanoparticles Formed on Al2O3 by High-Temperature H2 Reduction and Its Impact on Three-Way Catalysis

Thermostable Rh Metal Nanoparticles Formed on Al2O3 by High-Temperature H2 Reduction and Its Impact on Three-Way Catalysis

Pd/SrFe1–xTixO3−δ as Environmental Catalyst: Purification of Automotive Exhaust Gases

Low‐Temperature CO Oxidation by the Pt/CeO2 Based Catalysts

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Thermostable Rh Metal Nanoparticles Formed on Al₂O₃ by High-Temperature H₂ Reduction and Its Impact on Three-Way Catalysis

Thermostable Rh Metal Nanoparticles Formed on Al₂O₃ by High-Temperature H₂ Reduction and Its Impact on Three-Way Catalysis

Pd/SrFe_1–xTi_xO_3−δ as Environmental Catalyst: Purification of Automotive Exhaust Gases

Low‐Temperature CO Oxidation by the Pt/CeO₂ Based Catalysts