Development of Emission Control Systems to Enable High NO<sub>x</sub> Conversion on Heavy Duty Diesel Engines

Naseri, Mojghan; Conway, Raymond; Hess, Howard; Aydin, Ceren; Chatterjee, Sougato

doi:10.4271/2014-01-1525

Cited by 17 publications

(13 citation statements)

References 6 publications

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“…The premise is that, with the SCR layer on the DPF (SCRF), the exhaust temperature is high enough for better NO x reduction, and mass transfer limitations may be reduced because the flow of gases would be forced through the filter walls . Using the SCRF alone could not achieve the desired NO x reduction, so an additional SCR catalyst was required downstream, but this still enabled a total reduction of SCR catalyst volume . This volume reduction is limited by the filter porosity; a high porosity filter is required to increase SCR catalyst loading without causing excessive back pressure .…”

Section: Diesel Particulate Filter (Dpf) Catalytic Soot Filter (Csf)mentioning

confidence: 99%

“…Using the SCRF alone could not achieve the desired NO x reduction, so an additional SCR catalyst was required downstream, but this still enabled a total reduction of SCR catalyst volume . This volume reduction is limited by the filter porosity; a high porosity filter is required to increase SCR catalyst loading without causing excessive back pressure . In comparing SCRF to CSF, soot combustion efficiency was much higher with the CSF due to continuous NO oxidation, which introduces an intuitive trade‐off between using the two technologies .…”

Section: Diesel Particulate Filter (Dpf) Catalytic Soot Filter (Csf)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: Diesel Particulate Filter (Dpf) Catalytic Soot Filter (Csf)mentioning

confidence: 99%

Section: Diesel Particulate Filter (Dpf) Catalytic Soot Filter (Csf)mentioning

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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“…In previous paper [9], it was shown that the best system for high NOx conversion is a combination of DOC, SCR-DPF, and SCR on high porosity high cell density SCR catalyst. In the current work, two systems were utilized; they consisted of 1) diesel oxidation catalyst (DOC), SCR coated on DPF or SCR-DPF system and a high porosity, high cell density SCR catalyst, and 2) Cold Start Concept catalyst, SCR-DPF system and, a high porosity high cell density SCR catalyst.…”

Section: Methodsmentioning

confidence: 99%

Development of Emission Control Systems to Enable High NO_x Conversion on Heavy Duty Diesel Engines

Naseri

Aydin

Mulla

et al. 2015

SAE Int. J. Engines

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To meet NO x emission requirements and regulations for heavy duty diesel engines, selective catalytic reduction (SCR) has been demonstrated to be an effective solution. With increasing demand for improved fuel economy there is a desire to improve the NO x emission reduction of the SCR system, thus allowing for higher engine out NO x emissions. Such requirements will challenge the current aftertreatment designs, which consist of DOC, catalyzed soot filter (CSF) and SCR units. One approach is to replace the CSF with a diesel particulate filter coated with SCR (SCR-DPF) while keeping the flow-through SCR downstream. The downstream SCR can also be improved by using a highly porous flow-through substrate coated with higher washcoat loadings than those typically used on standard substrates today. This design will not only allow for improvement of NO x conversion at low temperature since the SCR-DPF unit will be closer to turbo out, but also an increased number of SCR active sites can be placed in the overall system without increasing the packing size in a typical 2010/13 system and thus provide high NO x conversion. For the SCR-DPF technology, high porosity filters are needed to enable the use of the higher catalytic loadings necessary to get good performance and durability. These highly porous filters need to have very good thermo mechanical properties to enable them to survive the active regeneration events over the life of the system. Also, a novel catalyst known as diesel Cold Start Concept (dCSC™) ABSTRACT Selective Catalytic Reduction (SCR) systems have been demonstrated as effective solutions for controlling NO x emissions from Heavy Duty diesel engines. Future HD diesel engines are being designed for higher engine out NO x to improve fuel economy, while discussions are in progress for tightening NO x emissions from HD engines post 2020. This will require increasingly higher NO x conversions across the emission control system and will challenge the current aftertreatment designs. Typical 2010/2013 Heavy Duty systems include a diesel oxidation catalyst (DOC) along with a catalyzed diesel particulate filter (CDPF) in addition to the SCR sub-assembly. For future aftertreatment designs, advanced technologies such as cold start concept (dCSC™) catalyst, SCR coated on filter (SCRF ® hereafter referred to as SCR-DPF) and SCR coated on high porous flow through substrates can be utilized to achieve high NO x conversions, in combination with improved control strategies.The objective of this work is to evaluate different advanced emission control system options in order to meet future high NO x conversions.First, high performance NO x control system architecture was designed by using a combination of dCSC catalyst, SCR-DPF filter system and high performance SCR on high porosity substrates. In this architecture, dCSC technology stores NO x during cold start when system is cold for any SCR reaction and then releases when the system warms up to allow NO x reduction across the SCR-DPF filter. The SCR-DPF filter enables lower t...

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“…Since the SCR substrate is located downstream of DPF, temperature increase at cold start takes longer time, and SCR catalyst cannot convert NOx during heat up. [3,4] Particularly, challenge 2 is a big challenge to comply with future regulations in which high NOx conversion capability is required in a wide variety of driving situations including cold start. Additionally, engine exhaust gas temperature will be lower because engine developers will choose lower CO2 engine calibration for future regulation.…”

Section: Introductionmentioning

confidence: 99%

Development of New High Porosity Diesel Particulate Filter for Integrated SCR Technology/Catalyst

Jin

Shinoda

Uesaka

et al. 2015

SAE Int. J. Fuels Lubr.

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Since the implementation of Euro 6 in September 2014, diesel engines are facing another drastic reduction of NOx emission limits from 180 to only 80 mg/km during NEDC and real driving emissions (RDE) are going to be monitored until limit values are enforced from September 2017. Considering also long term CO2 targets of 95 g/km beyond 2020, diesel engines must become cleaner and more efficient. However, there is a tradeoff between NOx and CO2 and, naturally, engine developers choose lower CO2 because NOx can be reduced by additional devices such as EGR or a catalytic converter. Lower CO2 engine calibration, unfortunately, leads to lower exhaust gas temperatures, which delays the activation of the catalytic converter. In order to overcome both problems, higher NOx engine out emission and lower exhaust gas temperatures, new aftertreatment systems will incorporate close-coupled DeNOx systems.Since the majority of current diesel emission control systems feature a close-coupled DOC+DPF converter, it seems to be a natural evolutionary step for NOx emission reduction to integrate the SCR catalyst technology onto the DPF.A high SCR catalyst loading will be required to have high conversion efficiency, however, higher loading amount causes high pressure drop for conventional DPF materials. Therefore a high porosity DPF design has been developed to overcome the tradeoff between high pressure drop, high washcoat loadings, and sufficient soot filtration efficiency. This paper will describe the advanced high porosity DPF for an integrated SCR concept including test results and future outlook.

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Development of Emission Control Systems to Enable High NO_x Conversion on Heavy Duty Diesel Engines

Cited by 17 publications

References 6 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

Development of Emission Control Systems to Enable High NO_x Conversion on Heavy Duty Diesel Engines

Development of New High Porosity Diesel Particulate Filter for Integrated SCR Technology/Catalyst

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Development of Emission Control Systems to Enable High NOx Conversion on Heavy Duty Diesel Engines

Cited by 17 publications

References 6 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

Development of Emission Control Systems to Enable High NOx Conversion on Heavy Duty Diesel Engines

Development of New High Porosity Diesel Particulate Filter for Integrated SCR Technology/Catalyst

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Development of Emission Control Systems to Enable High NO_x Conversion on Heavy Duty Diesel Engines

Development of Emission Control Systems to Enable High NO_x Conversion on Heavy Duty Diesel Engines