Studies on the structural evolution of highly active Ir-based catalysts for the selective reduction of NO with reductants in oxidizing conditions

Tadao Nakatsuji

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

NOx reduction over Ir-based catalysts in the presence of excess oxygen with hydrocarbon as a reductant was investigated in the focus on observing microstructure of an Ir particle supported on various carriers and structural evolution of highly active Ir-based catalysts in the NOx reduction. Characterization of Ir-based catalysts using SEM, TEM, XRD, CO chemisorption and XPS, and reaction studies on various Ir-based catalysts have proved that the formation of a relatively large Ir metal particle with 40–60 nm of nanocrystal size carried on inert supports has been a prerequisite for the evolution of high activities in the NOx reduction rather than the formation of Ir metal state on the catalyst. Furthermore, in inert gas conditions in a high temperature range of 850–950°C, Ir metal was easily formed by using the support such as TiO2 and ZrO2 that drastically decreased its specific surface area in the temperature range.

Original languageEnglish
Pages (from-to)163 - 179
Number of pages17
JournalApplied Catalysis B: Environmental
Volume25
Issue number2-3
DOIs
Publication statusPublished - 2000
MoE publication typeA1 Journal article-refereed

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Reducing Agents
catalyst
Catalysts
Metals
metal
Noble Gases
Carbon Monoxide
Chemisorption
Inert gases
Hydrocarbons
Specific surface area
Nanocrystals
X-ray spectroscopy
transmission electron microscopy
microstructure
X ray photoelectron spectroscopy
surface area
scanning electron microscopy
X-ray diffraction
hydrocarbon

Cite this

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abstract = "NOx reduction over Ir-based catalysts in the presence of excess oxygen with hydrocarbon as a reductant was investigated in the focus on observing microstructure of an Ir particle supported on various carriers and structural evolution of highly active Ir-based catalysts in the NOx reduction. Characterization of Ir-based catalysts using SEM, TEM, XRD, CO chemisorption and XPS, and reaction studies on various Ir-based catalysts have proved that the formation of a relatively large Ir metal particle with 40–60 nm of nanocrystal size carried on inert supports has been a prerequisite for the evolution of high activities in the NOx reduction rather than the formation of Ir metal state on the catalyst. Furthermore, in inert gas conditions in a high temperature range of 850–950°C, Ir metal was easily formed by using the support such as TiO2 and ZrO2 that drastically decreased its specific surface area in the temperature range.",
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journal = "Applied Catalysis B: Environmental",
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Studies on the structural evolution of highly active Ir-based catalysts for the selective reduction of NO with reductants in oxidizing conditions. / Nakatsuji, Tadao.

In: Applied Catalysis B: Environmental, Vol. 25, No. 2-3, 2000, p. 163 - 179.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

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AB - NOx reduction over Ir-based catalysts in the presence of excess oxygen with hydrocarbon as a reductant was investigated in the focus on observing microstructure of an Ir particle supported on various carriers and structural evolution of highly active Ir-based catalysts in the NOx reduction. Characterization of Ir-based catalysts using SEM, TEM, XRD, CO chemisorption and XPS, and reaction studies on various Ir-based catalysts have proved that the formation of a relatively large Ir metal particle with 40–60 nm of nanocrystal size carried on inert supports has been a prerequisite for the evolution of high activities in the NOx reduction rather than the formation of Ir metal state on the catalyst. Furthermore, in inert gas conditions in a high temperature range of 850–950°C, Ir metal was easily formed by using the support such as TiO2 and ZrO2 that drastically decreased its specific surface area in the temperature range.

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