A NOx reduction system using ammonia-storage selective catalytic reduction in rich/lean excursions

Nakatsuji, Tadao; Matsubara, Manabu; Rouistenmäki, Juhana; Sato, Naohiro; Ohno, Hiroshi

doi:10.1016/j.apcatb.2007.07.018

Cited by 44 publications

(21 citation statements)

References 21 publications

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“…[96] Increasing the number of zones from 2, 4, and 8-zoned led to lower N 2 O and NH 3 emissions; the SCR zones were able to reduce NO X with NH 3 and avoid N 2 O formation over the LNT zones. [80] A dual layer architecture was investigated by Honda R & D Co., Ltd. [97][98][99] and others. [100][101][102][103] In the dual layered configuration, the LNT is the bottom layer and the SCR is the top layer.…”

Section: Lean No X Trap (Lnt) and Lnt-scrmentioning

confidence: 99%

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: Lean No X Trap (Lnt) and Lnt-scrmentioning

confidence: 99%

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

Hazlett

Epling

2018

Can J Chem Eng

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“…To avoid the NH3 break-out, one possibility is to combine the NSR catalyst with a SCR system. The NH3 is stored during the rich phase on the SCR catalyst sites and used as a reducer for SCR reaction at the beginning of the next lean cycle [3,4]. In this approach, we investigated the influence of the addition of CuZSM-5 to a model Pt-Rh/Ba/Al NSR catalyst in order to determine if the NOx removal under lean-rich atmosphere can be efficiently improved.…”

Section: Introductionmentioning

confidence: 99%

Cooperative effect of Pt–Rh/Ba/Al and CuZSM-5 catalysts for NO reduction during periodic lean-rich atmosphere

Corbos¹,

Haneda²,

Courtois³

et al. 2008

Catalysis Communications

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NOx removal efficiency was investigated with a combination of model Pt-Rh/Ba/Al and Cu-ZSM-5 catalysts using periodic fluctuations between lean (100 s) and rich (10 s) atmosphere. NOx removal is greatly improved at 250°C and 300°C by physically mixing the two catalysts. The mixed catalyst shows a NOx removal activity almost double as compared to a system where Pt-Rh/Ba/Al catalyst is situated upstream and CuZSM-5 downstream the gas flow. FT-IR characterization shows that CuZSM-5 catalyst enhances the formation of NCO species on alumina during rich conditions. These NCO are further hydrolyzed to NH3 under lean condition which acts as a reductant for NOx.

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“…With high blend ratios of 70/WPPO15/E15, 60/WPPO20/E20, and 50/ WPPO25/E25, the combustion process is shortened, thus leading to failure to provide enough cooling effect to decrease peak combustion temperatures leading to increased NO X . The concept of employing a NO X absorber with a double SCR layer configuration [109]. These findings seem to show that there is a correlation between the alcohol content in the fuel and peak flame temperatures, content of nitrogen, and oxygen availability [123].…”

Section: Nitrogen Oxide (No X ) Concentrationmentioning

confidence: 99%

Effects of Biodiesel Blends Varied by Cetane Numbers and Oxygen Contents on Stationary Diesel Engine Performance and Exhaust Emissions

Maroa¹,

Inambao²

2020

Numerical and Experimental Studies on Combustion Engines and Vehicles

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This work investigated waste plastic pyrolysis oil (WPPO), 2-ethyl hexyl nitrate (EHN), and ethanol as sources of renewable energy, blending conventional diesel (CD), WPPO, and ethanol with EHN was to improve the combustion and performance characteristics of the WPPO blends. EHN has the potential to reduce emissions of CO, CO2, UHC, NOX, and PM. Ethanol improves viscosity, miscibility, and the oxygen content of WPPO. Mixing ratios were 50/WPPO25/E25, 60/WPPO20/E20, 70/WPPO15/E15, 80/WPPO10/E10, and 90/WPPO5/E5 for CD, waste plastic pyrolysis oil, and ethanol, respectively. The mixing ratio of EHN (0.01%) was based on the total quantity of blended fuel. Performance and emission characteristics of a stationary 4-cylinder water-cooled diesel Iveco power generator were evaluated with ASTM standards. At 1000 rpm, the BSFC was 0.043 kg/kWh compared to CD at 0.04 kg/kWh. Blend 90/WPPO5/E5 had the highest value of 14% for BTE, while the NOX emissions for 90/WPPO5/E5, 80/WPPO10/E10, and 70/WPPO15/E15 were 384, 395, and 414 ppm, respectively, compared to CD fuel at 424 ppm. This is due to their densities of 792 kg/m3, 825 kg/m3 which are close to CD fuel at 845 kg/m3 and the additive EHN. These results show blends of WPPO, ethanol and EHN reduce emissions, and improve engine performance, mimicking CD fuel.

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A NOx reduction system using ammonia-storage selective catalytic reduction in rich/lean excursions

Cited by 44 publications

References 21 publications

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

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

Cooperative effect of Pt–Rh/Ba/Al and CuZSM-5 catalysts for NO reduction during periodic lean-rich atmosphere

Effects of Biodiesel Blends Varied by Cetane Numbers and Oxygen Contents on Stationary Diesel Engine Performance and Exhaust Emissions

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