Development of the Design Methodology for a New De-NOx System

Uenishi, Toru; Umemoto, Kazuhiro; Yoshida, Kohei; Itoh, Takekazu; Fukuma, Takao

doi:10.20485/jsaeijae.5.3_115

Cited by 10 publications

(2 citation statements)

References 6 publications

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“…HC premixed in the rich line also helps avoid flow maldistribution. This was important as Toyota researchers recently pointed out that high radial uniformity of HC concentration was essential for Di-Air performance [23]. In order to minimize upstream axial mixing of lean and rich streams, the switching valve was placed close to the monolith catalyst (~ 0.6 m upstream), but sufficiently far to enable sufficient preheating of the feed stream.…”

Section: Reactor Systemmentioning

confidence: 99%

Rapid propylene pulsing for enhanced low temperature NO conversion on combined LNT-SCR catalysts

Zheng

Wang

et al. 2016

Catalysis Today

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Lean reduction of NOx (NO + NO 2) was conducted over combined LNT-SCR dual-layer and zoned monolithic catalysts using rapid propylene periodic pulsing into a lean feed. We investigated the effects of cycling frequency, reaction exotherm, hydrocarbon (HC) intermediates, top-layer material, LNT ceria content and catalyst configuration on the performance of dual-layer catalysts under fast propylene pulsing. High frequency propylene injection expands the operating temperature window of a conventional NOx storage and reduction (NSR) system in both low and high-temperature regions. The combination of rapid propylene pulsing and the dual-layer catalyst architecture achieves a low-temperature NOx conversion of up to 80% at a feed temperature of ca. 200 °C and relevant space velocities (~ 70k h −1). The working mechanisms of rapid propylene pulsing on both LNT and LNT-SCR catalysts are discussed. Fast cycling facilitates the generation of partially oxidized hydrocarbon intermediates over the LNT that can then either directly react with NOx or act as oxygen scavenger to maintain Pt in a reduced state for direct NO decomposition. The SCR top-layer traps partially oxygenated species that desorb from the LNT layer, enabling further production of N 2 through a LNT-assisted HC-SCR pathway. Optimization of ceria content, top-layer material and catalyst configuration like SCR and PGM zoning can improve system performance at lower cost.

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Section: Reactor Systemmentioning

confidence: 99%

Rapid propylene pulsing for enhanced low temperature NO conversion on combined LNT-SCR catalysts

Zheng

Wang

et al. 2016

Catalysis Today

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“…Effective methods have been developed to address these issues through a combination of experiments and simulations. [12][13][14][15][16] Moreover, the convection and diffusion of reactive molecules in the channels and catalytic coating of the honeycomb substrate are imperative. Several experimental and numerical approaches are underway to address this problem.…”

Section: Introductionmentioning

confidence: 99%

Study on the effect of hydrocarbon structure on the reactivity of the three-way catalytic converter

Uenishi

2022

International Journal of Engine Research

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The effect of hydrocarbon structures on reduction of nitric oxide and oxidation of carbon monoxide and hydrocarbons on the palladium-rhodium catalyst supported on aluminum-cerium-zirconium oxide was examined with fixed-bed flow reactor using synthetic gas. As regards olefinic hydrocarbons, the lower the number of carbon atoms, the higher the rate of reduction of nitric oxide, the lower the number of carbon atoms, the greater the rate of oxidation of hydrocarbons and carbon monoxide. Olefinic hydrocarbons have a π bond and are highly adsorbed on catalytic sites. Consequently, it may be hypothesized that if the number of carbon atoms increases, the adsorption ability becomes too high and the reactivity of the hydrocarbons decreases. On the other hand, for paraffinic hydrocarbons, the greater the number of carbon atoms, the greater the rate of reduction of nitric oxide, and the more carbon atoms there are, the higher the oxidation rate of the hydrocarbon. In the case of paraffinic hydrocarbons, there are only σ bonds and less adsorption on the catalyst site, it is therefore assumed that the greater the number of carbon atoms, the greater the reactivity of the hydrocarbon. The results of the effects of these hydrocarbon structures on the overall three-way catalytic reaction activity provide an indicator of the development of new catalysts.

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Fast Cycling NOx Storage and Reduction: Identification of an Adsorbed Intermediate Pathway

2018

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Development of the Design Methodology for a New De-NOx System

Cited by 10 publications

References 6 publications

Rapid propylene pulsing for enhanced low temperature NO conversion on combined LNT-SCR catalysts

Rapid propylene pulsing for enhanced low temperature NO conversion on combined LNT-SCR catalysts

Study on the effect of hydrocarbon structure on the reactivity of the three-way catalytic converter

Fast Cycling NOx Storage and Reduction: Identification of an Adsorbed Intermediate Pathway

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