Dual-layer automotive catalysts - effect of transport limitation on NOx reduction

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Dual-layer automotive catalysts - effect of transport limitation on NOx reduction

Popis výsledku v původním jazyce

Exhaust gas aftertreatment system of a modern Diesel engine consists of a particulate filter and a succession of different catalytic converters. In order to save space and minimize heat losses there is an effort to combine catalysts with different functions in a single monolith reactor coated with multiple layers of different catalysts. However, when the porous layer is too thick, the overall efficiency of the converter is lowered by transport limitations. This work investigates diffusion limitations in dual-layer catalytic converters. LNT coated monoliths were overlaid either with inert (denoted LNT+IN), or an oxidation catalyst (LNT+DOC) to decouple the transport and kinetic effects. The samples were characterised and tested in a laboratory reactor for oxidation reactions and NOx removal. Additional layers brought about changes in the selectivity, longer delay of NH3 breakthrough or shift of N2O formation from primary to secondary peak. While the IN layer lowered overall NOx conversion, the DOC layer addition had both positive (catalytic activity) and negative (transport) effects. At lower temperature NOx storage and regeneration efficiency were improved, whereas at higher temperature, when the LNT itself was active enough, transport limitation in the DOC layer becomes the rate determining step.

Název v anglickém jazyce

Dual-layer automotive catalysts - effect of transport limitation on NOx reduction

Popis výsledku anglicky

Exhaust gas aftertreatment system of a modern Diesel engine consists of a particulate filter and a succession of different catalytic converters. In order to save space and minimize heat losses there is an effort to combine catalysts with different functions in a single monolith reactor coated with multiple layers of different catalysts. However, when the porous layer is too thick, the overall efficiency of the converter is lowered by transport limitations. This work investigates diffusion limitations in dual-layer catalytic converters. LNT coated monoliths were overlaid either with inert (denoted LNT+IN), or an oxidation catalyst (LNT+DOC) to decouple the transport and kinetic effects. The samples were characterised and tested in a laboratory reactor for oxidation reactions and NOx removal. Additional layers brought about changes in the selectivity, longer delay of NH3 breakthrough or shift of N2O formation from primary to secondary peak. While the IN layer lowered overall NOx conversion, the DOC layer addition had both positive (catalytic activity) and negative (transport) effects. At lower temperature NOx storage and regeneration efficiency were improved, whereas at higher temperature, when the LNT itself was active enough, transport limitation in the DOC layer becomes the rate determining step.

Druh

D - Stať ve sborníku

CEP obor

CI - Průmyslová chemie a chemické inženýrství

OECD FORD obor

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Projekt

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Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

Proceedings 43rd International Conference of the Slovak Society of Chemical Engineering

ISBN

978-80-89597-35-2

ISSN

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e-ISSN

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Počet stran výsledku

9

Strana od-do

640-649

Název nakladatele

Slovak Society of Chemical Engineering

Místo vydání

Bratislava

Místo konání akce

Tatranské Matliare

Datum konání akce

23. 5. 2016

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

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