The Effects of CO, H2, and C3H6 on the SCR Reactions of an Fe Zeolite SCR Catalyst

Smith, Michael A.; Depcik, Christopher; Hoard, John; Bohac, Stani; Assanis, Dennis N.

doi:10.4271/2013-01-1062

Cited by 4 publications

(1 citation statement)

References 35 publications

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“…In case of CO emissions, only downstream values are shown in Figure 11 because of the negligible effect of the SCR catalyst on this compound. 37 As observed, tailpipe CO emissions were very small and only noticeable during the first instants of the low speed phase, because the light-off temperature of the DOC was not reached yet. Obviously, this effect is more significant at 27°C.…”

Section: Gaseous Emissionsmentioning

confidence: 69%

Effect of advanced biofuels on WLTC emissions of a Euro 6 diesel vehicle with SCR under different climatic conditions

Calle-Asensio

Hernández

Rodríguez–Fernández

et al. 2021

International Journal of Engine Research

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Hydrotreated vegetable oil (HVO), a glycerol-derived biofuel (blended with diesel fuel at 20% v/v, Mo·bio®) and biodiesel produced through the esterification of residual free fatty acids from the palm oil industry (pure and blended with diesel fuel at 20% v/v), all of them considered as advanced biofuels as defined in the Directive EU/2018/2001, were tested in a Euro 6 diesel vehicle equipped with ammonia-SCR. Tests were carried out in a chassis dyno at warm (24°C) and cold (−7°C) ambient conditions following the Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). The efficiency of the SCR when changing the fuel was also analysed. Regarding vehicle performance, fuel properties were mainly relevant at warm conditions. Because of the lower EGR rate, NOx emissions upstream of the SCR were higher at cold temperature, mainly during the low and the extra-high speed phases of the WLTC. CO and THC emissions were only important at the beginning of the cycle and at −7°C. HVO presented advantages regarding these compounds, while the worse cloud point of biodiesel led to higher emissions. As expected, engine-out NOx emissions were very sensitive to the EGR rate, HVO showing a slightly better behaviour because of its high cetane number. The SCR efficiency was mainly affected by the exhaust gas temperature, although fuel-derived effects were also significant. In fact, a more appropriate NO2/NOx ratio at the catalyst inlet for HVO and a higher hydrocarbon concentration at the low-speed phase for B20 contributed to a lower tail-pipe NOx emissions at −7°C. The oxygen content of biodiesel-based fuels (B100 and B20) led to lower particle number with respect to diesel fuel. Despite its nil aromatic content, the higher EGR rate and the extremely superior autoignition trend of HVO led to higher particle number under high engine load and warm conditions.

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Section: Gaseous Emissionsmentioning

confidence: 69%

Effect of advanced biofuels on WLTC emissions of a Euro 6 diesel vehicle with SCR under different climatic conditions

Calle-Asensio

Hernández

Rodríguez–Fernández

et al. 2021

International Journal of Engine Research

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Three Way Catalyst-Selective Catalytic Reduction Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in Homogenous Charge Compression Ignition, Spark-Assisted Compression Ignition, and Spark-Ignited Combustion Modes

Easter

Bohac

2018

Journal of Engineering for Gas Turbines and Power

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Low temperature and dilute homogenous charge compression ignition (HCCI) and spark-assisted compression ignition (SACI) can improve fuel efficiency and reduce engine-out NOx emissions, especially during lean operation. However, under lean operation, these combustion modes are unable to achieve Environmental Protection Agency (EPA) Tier 3 emissions standards without the use of lean aftertreatment. The three way catalyst (TWC)-SCR lean aftertreatment concept investigated in this work uses periodic-rich operation to produce NH3 over a TWC to be stored on a selective catalytic reduction (SCR) catalyst for NOx conversion during subsequent lean operation. Experiments were performed with a modified 2.0 L gasoline engine that was cycled between lean HCCI and rich SACI operation and between lean and rich spark-ignited (SI) combustion to evaluate NOx conversion and fuel efficiency benefits. Different lambda values during rich operation and different times held in rich operation were investigated. Results are compared to a baseline case in which the engine is always operated at stoichiometric conditions. SCR system calculations are also presented to allow for comparisons of system performance for different levels of stored NH3. With the configuration used in this study, lean/rich HCCI/SACI operation resulted in a maximum NOx conversion efficiency of only 10%, while lean/rich SI operation resulted in a maximum NOx conversion efficiency of 60%. If the low conversion efficiency of HCCI/SACI operation could be improved through higher brick temperatures or additional SCR bricks, calculations indicate that TWC-SCR aftertreatment has the potential to provide attractive fuel efficiency benefits and near-zero tailpipe NOx. Calculated potential fuel efficiency improvement relative to stoichiometric SI is 7–17% for lean/rich HCCI/SACI with zero tailpipe NOx and −1 to 5% for lean/rich SI with zero tailpipe NOx emissions. Although the previous work indicated that the use of HCCI/SACI increases the time for NH3 to start forming over the TWC during rich operation, reduces NH3 production over the TWC per fuel amount, and increases NH3 slip over the SCR catalyst, if NOx conversion efficiency could be enhanced, improvements in fuel efficiency could be realized while meeting stringent tailpipe NOx standards.

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Influence of HCCI and SACI Combustion Modes on NH₃ Generation and Subsequent Storage across a TWC-SCR System

Easter

Bohac

2016

SAE Technical Paper Series

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The Effects of CO, H₂, and C₃H₆ on the SCR Reactions of an Fe Zeolite SCR Catalyst

Cited by 4 publications

References 35 publications

Effect of advanced biofuels on WLTC emissions of a Euro 6 diesel vehicle with SCR under different climatic conditions

Effect of advanced biofuels on WLTC emissions of a Euro 6 diesel vehicle with SCR under different climatic conditions

Three Way Catalyst-Selective Catalytic Reduction Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in Homogenous Charge Compression Ignition, Spark-Assisted Compression Ignition, and Spark-Ignited Combustion Modes

Influence of HCCI and SACI Combustion Modes on NH₃ Generation and Subsequent Storage across a TWC-SCR System

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The Effects of CO, H2, and C3H6 on the SCR Reactions of an Fe Zeolite SCR Catalyst

Cited by 4 publications

References 35 publications

Effect of advanced biofuels on WLTC emissions of a Euro 6 diesel vehicle with SCR under different climatic conditions

Effect of advanced biofuels on WLTC emissions of a Euro 6 diesel vehicle with SCR under different climatic conditions

Three Way Catalyst-Selective Catalytic Reduction Aftertreatment System Evaluation for a Lean Burn Gasoline Engine Operating in Homogenous Charge Compression Ignition, Spark-Assisted Compression Ignition, and Spark-Ignited Combustion Modes

Influence of HCCI and SACI Combustion Modes on NH3 Generation and Subsequent Storage across a TWC-SCR System

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Product

Resources

About

The Effects of CO, H₂, and C₃H₆ on the SCR Reactions of an Fe Zeolite SCR Catalyst

Influence of HCCI and SACI Combustion Modes on NH₃ Generation and Subsequent Storage across a TWC-SCR System