Hauptmann, Gerhart

Scheuer, Helmut

doi:10.1007/978-3-476-03720-6_158

Cited by 1 publication

(4 citation statements)

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“…Another possible benefit of the layered configuration would be NO oxidation to NO 2 in the bottom layer, which would promote fast SCR reactions on the SCR top layer, though this modelling study concluded that this pathway does not play a significant role with the catalyst's current NO oxidation capacity. [70] Overall, this study showed that the dual layered design showed higher N 2 selectivity, but lower NH 3 conversion than the oxidation catalyst alone.…”

Section: Ammonia Slip Catalyst (Asc)mentioning

confidence: 67%

“…It typically contains a SCR catalyst with an oxidation catalyst like Pt/Al 2 O 3 . [70] Implementing an ASC downstream of the SCR to oxidize extra ammonia that slips past the SCR enables extra ammonia dosing, i.e., higher than the stoichiometric amount required, helping to reach maximum NO x conversion. The overall reaction on the ASC to oxidize NH 3 to N 2 is:…”

Section: Ammonia Slip Catalyst (Asc)mentioning

confidence: 99%

“…In a dual layer SCR/oxidation catalyst study, a dual layer Fe/zeolite SCR and Pt/Al 2 O 3 oxidation catalyst was tested along with a single layer oxidation catalyst for comparison, [70] and modelled using a previously developed mechanistic kinetic model. [74] Both modelling and experiment showed that the top SCR layer introduced diffusion limitations, which had a significant negative impact on the ammonia oxidation in the bottom Pt/Al 2 O 3 layer, the extent of which depended on the SCR layer thickness.…”

Section: Ammonia Slip Catalyst (Asc)mentioning

confidence: 99%

“…[74] Both modelling and experiment showed that the top SCR layer introduced diffusion limitations, which had a significant negative impact on the ammonia oxidation in the bottom Pt/Al 2 O 3 layer, the extent of which depended on the SCR layer thickness. [70] When the SCR catalyst loading was reduced, ammonia oxidation increased. Furthermore, ammonia conversion was improved at lower gas space velocities, supporting the diffusion limitation hypothesis.…”

Section: Ammonia Slip Catalyst (Asc)mentioning

confidence: 99%

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Heterogeneous catalyst design: Zoned and layered catalysts in diesel vehicle aftertreatment monolith reactors

Hazlett

Epling

2018

Can J Chem Eng

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There have been ongoing research efforts focused on layering or zoning different washcoats/active metals on the catalysts constituting diesel aftertreatment systems: the diesel oxidation catalyst (DOC), the selective catalytic reduction (SCR) catalyst, the lean NOX trap (LNT), the ammonia slip catalyst (ASC), and the diesel particulate filter (DPF). This review paper aims to shed insight into the state‐of‐the‐art research on catalyst design in this area and how these catalyst designs may evolve to tackle engine emission reductions in the future. First, we discuss the motivation for zoning or layering catalysts and pioneering work on three‐way catalyst (TWC) design for reducing gasoline engine emissions; then, we focus on the catalytic systems used for diesel exhaust aftertreatment. The configuration of the aftertreatment systems for diesel engines generally consist of an oxidation catalyst for hydrocarbon (HC), CO, and NO oxidation (over the DOC), a NOX reduction catalyst (over one or combined SCR/LNT/ASC catalysts), and a particulate matter (PM) filter (using a DPF). The research to date consistently demonstrates that zoning and layering catalyst regions leads to improved performance and/or smaller system volumes required.

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Section: Ammonia Slip Catalyst (Asc)mentioning

confidence: 67%

Section: Ammonia Slip Catalyst (Asc)mentioning

confidence: 99%