New technology for selective catalytic oxidation of ammonia to nitrogen

Ueshima, Michio; Sano, Kohei; Ikeda, M.; Yoshino, Kenji; Okamura, Junji

doi:10.1163/156856798x00726

Cited by 17 publications

(7 citation statements)

References 8 publications

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“…The same chemistry, when, for example NH 3 slip elimination is concerned, is termed ''selective catalytic oxidation (SCO)'' instead. 149,[158][159][160][161][162][163] While performance types of studies are abundant, mechanistic studies for this reaction are surprisingly scarce. 158,162…”

Section: Nh 3 Oxidationmentioning

confidence: 99%

Recent advances in automotive catalysis for NO_x emission control by small-pore microporous materials

et al. 2015

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The ever increasing demand to develop highly fuel efficient engines coincides with the need to minimize air pollution originating from the exhaust gases of internal combustion engines. Dramatically improved fuel efficiency can be achieved at air-to-fuel ratios much higher than stoichiometric. In the presence of oxygen in large excess, however, traditional three-way catalysts are unable to reduce NOx. Among the number of lean-NOx reduction technologies, selective catalytic reduction (SCR) of NOx by NH3 over Cu- and Fe-ion exchanged zeolite catalysts has been extensively studied over the past 30+ years. Despite the significant advances in developing a viable practical zeolite-based catalyst for lean NOx reduction, the insufficient hydrothermal stabilities of the zeolite structures considered cast doubts about their real-world applicability. During the past decade renewed interest in zeolite-based lean NOx reduction was spurred by the discovery of the very high activity of Cu-SSZ-13 (and the isostructural Cu-SAPO-34) in the NH3-SCR of NOx. These new, small-pore zeolite-based catalysts not only exhibited very high NOx conversion and N2 selectivity, but also exhibited exceptionally high hydrothermal stability at high temperatures. In this review we summarize the key discoveries of the past ∼5 years that led to the introduction of these catalysts into practical applications. This review first briefly discusses the structure and preparation of the CHA structure-based zeolite catalysts, and then summarizes the key learnings of the rather extensive (but not complete) characterisation work. Then we summarize the key findings of reaction kinetic studies, and provide some mechanistic details emerging from these investigations. At the end of the review we highlight some of the issues that still need to be addressed in automotive exhaust control catalysis.

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Section: Nh 3 Oxidationmentioning

confidence: 99%

Recent advances in automotive catalysis for NO_x emission control by small-pore microporous materials

et al. 2015

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“…In addition, the “strong metal support interaction” (SMSI) effect ascribed to TiO 2 16,27,28 and the observation that transition metals supported on titania−silica exhibit higher activities than on silica alone − show the great potential of these materials as support.…”

Section: Introductionmentioning

confidence: 99%

“…They have stronger acidic properties than the composing single oxides caused by the formation of nonequivalent bridged heterometal-oxygen-silicon bonds (M-O-Si), 14,25 and as such, they can be used as acidic catalysts. 21,26 In addition, the "strong metal support interaction" (SMSI) effect ascribed to TiO 2 16, 27,28 and the observation that transition metals supported on titania-silica exhibit higher activities than on silica alone [29][30][31][32] show the great potential of these materials as support.…”

Section: Introductionmentioning

confidence: 99%

Deposition of a Titania Coating on Silica by Means of the Chemical Surface Coating

1999

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A chemically bound TiO2 layer was created on silica by using a grafting method called “Chemical Surface Coating”. TiCl4 and H2O were used as reagents in successive cycles. The surface reactions and surface species attached to the silica were characterized by elemental analysis as well as X-ray diffraction, Fourier transform infrared, Raman, and UV-diffuse reflectance spectroscopy. The TiO x layer constitutes of nanoparticles of anatase homogeneously spread over the surface. Calcination of the TiO2−SiO2 materials leads to a particle size increase. An extensive pore size analysis was also undertaken to investigate the morphological changes as a function of the number of reaction cycles.

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“…Table 1 summarises the discussed catalyst systems. 8 In NH3-SCO, almost 100% conversion of ammonia is required in order to eliminate ammonia odor [116]. Altogether, a design of oxidation catalysts of high efficiency, selectivity to N2 and stability remains challenging.…”

Section: Catalytic Systemsmentioning

confidence: 99%

Copper based catalysts for the selective ammonia oxidation into nitrogen and water vapour—Recent trends and open challenges

Jabłońska

Palkovits

2016

Applied Catalysis B: Environmental

197

172

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New technology for selective catalytic oxidation of ammonia to nitrogen

Cited by 17 publications

References 8 publications

Recent advances in automotive catalysis for NO_x emission control by small-pore microporous materials

Recent advances in automotive catalysis for NO_x emission control by small-pore microporous materials

Deposition of a Titania Coating on Silica by Means of the Chemical Surface Coating

Copper based catalysts for the selective ammonia oxidation into nitrogen and water vapour—Recent trends and open challenges

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New technology for selective catalytic oxidation of ammonia to nitrogen

Cited by 17 publications

References 8 publications

Recent advances in automotive catalysis for NOx emission control by small-pore microporous materials

Recent advances in automotive catalysis for NOx emission control by small-pore microporous materials

Deposition of a Titania Coating on Silica by Means of the Chemical Surface Coating

Copper based catalysts for the selective ammonia oxidation into nitrogen and water vapour—Recent trends and open challenges

Contact Info

Product

Resources

About

Recent advances in automotive catalysis for NO_x emission control by small-pore microporous materials

Recent advances in automotive catalysis for NO_x emission control by small-pore microporous materials