SCR for Passenger Car: the Ammonia-Storage Issue on a Fe-ZSM5 Catalyst

Frobert, Arnaud; Creff, Yann; Raux, S.; Charial, Christophe; Audouin, Arnaud; Gagnepain, Laurent

doi:10.4271/2009-01-1929

Cited by 11 publications

(6 citation statements)

References 11 publications

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“…Consequently, the ammonia storage capacity of the select SCR would be considered as an important factor in selecting the right formulation of a passive reduction system. A study performed by Frobert et al indicated that the exhaust temperature, NO2/NOx ratio, and air mass flow were the three main parameters that influenced the ammonia storage characteristics (Frobert et al 2009). Studies have also shown ammonia storage capacity tend to be higher at lower catalyst temperatures and decreases as temperature increases (Li et al 2010).…”

Section: Figure 6 Nox Conversion Efficiency For Vanadium-based and Mmentioning

confidence: 99%

Development of an Ammonia Reduction Aftertreatment Systems for Stoichiometric Natural Gas Engines

Pradhan

Thiruvengadam

et al. 2017

SAE Int. J. Engines

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Development of an Ammonia Reduction After-treatment Systems for Stoichiometric Natural Gas Engines Saroj Pradhan Three-way catalyst (TWC) equipped stoichiometric natural gas vehicles have proven to be an effective alternative fuel strategy that shows significant low NOx emissions characteristics. However, recent studies have shown the TWC activity to contribute to elevated levels of tailpipe ammonia (NH3) emissions. Although a non-regulated pollutant, ammonia is a potent precursor to ambient secondary PM formation. Ammonia is an inevitable byproduct of fuel rich operation that results in lowest NOx slip through the TWC after-treatment system. The main objective of the study is to develop a passive Ammonia Reduction Catalyst (passive-ARC) based NH3 reduction strategy that results in an overall reduction of ammonia as well as NOx emissions. The study investigated the characteristics of Fe-based and Cu-based zeolites SCR catalysts in storage and desorption of ammonia at high exhaust temperature conditions, that are typical of stoichiometric natural gas engines. Continuous measurements of NOx and NH3 before and after the SCR systems were conducted using a Fourier Transform Infrared Spectrometry (FTIR) gas analyzer. Results of the investigation showed that both, the

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Section: Figure 6 Nox Conversion Efficiency For Vanadium-based and Mmentioning

confidence: 99%

Development of an Ammonia Reduction Aftertreatment Systems for Stoichiometric Natural Gas Engines

Pradhan

Thiruvengadam

et al. 2017

SAE Int. J. Engines

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“…A 3.3 L SCR converter is modeled in our study . In the rest of this article, the term “SCR convertor” refers to the convertor comprising an inlet diverging cone, a central catalytic monolith, and an outlet converging cone.…”

Section: Selective Catalytic Reduction (Scr) Modelmentioning

confidence: 99%

Modeling the Effect of Nonuniformities from Urea Injection on SCR Performance Using CFD

Dammalapati

Aghalayam

Kaisare

2019

Ind. Eng. Chem. Res.

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A computational fluid dynamics model, consisting of a mixing chamber coupled with a catalytic converter, is developed for the selective catalytic reduction (SCR) of NO x using urea. The NH3 required for the SCR reactions is produced from the injection and decomposition of urea in the mixing chamber. The conversion efficiency and concentration distribution of NH3 from the mixing chamber are analyzed for a range of operating conditions. The flow and species distribution profiles from the mixing chamber are incorporated as inlet boundary conditions at the entrance of the downstream SCR convertor. The SCR convertor comprises a central catalytic monolith and inlet and outlet diffuser sections. Variations in NO x concentration were observed within the monolith due to heat losses and nonuniformities in ammonia concentrations. While heat effects under non-isothermal conditions slightly improved the NO x conversion efficiency, nonuniformities in ammonia concentrations did not significantly influence the SCR performance. Thus, the radial variations in NH3 concentrations, owing to nonuniformity at the outlet of the mixing chamber, did not considerably impact the overall performance of the SCR. The effects of temperature, NO:NO2 ratio, and inlet velocity were investigated.

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“…However, experiments show that the desorbed amount of NH 3 is slightly lower than the adsorbed amount. One study refers to it as 'non thermally reversible storage of ammonia' [30]. The mathematical model, however, uses a simple Arrhenius-type reaction rate equation and a conservative form of species transport equation.…”

Section: Nh 3 Storage Capacitymentioning

confidence: 99%

Development and validation of a model for wall-flow type selective catalytic reduction system

Park

Rutland

Narayanaswamy

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part D:

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The two-way diesel particulate filter (DPF)/selective catalytic reduction (SCR) emissions-reduction system has recently been extensively studied due to its potential cost savings and packing flexibility. Unlike a conventional emissions-reduction system that consists of a DPF and an SCR for reduction of both particulate matter and nitrogen oxides (NO x ), this twoway system incorporates SCR function into a wall-flow DPF as a single device by coating SCR catalysts into the filter wall of the DPF. Such a combinatorial system has the advantage of lower system volume and cost, since exhaust gas undergoes soot filtering and NO x reduction reaction simultaneously as it passes through the channels and filter wall. In this work, the mathematical formulations which govern the physical and chemical phenomena in the twoway DPF/SCR are derived and a computer simulation model is developed based on these formulations. The model has been validated and tested with experimental data from a reactor flow bench in a systematic manner, which captures ammonia adsorption/desorption and NO x reduction of the blended two-way DPF/SCR device.

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SCR for Passenger Car: the Ammonia-Storage Issue on a Fe-ZSM5 Catalyst

Cited by 11 publications

References 11 publications

Development of an Ammonia Reduction Aftertreatment Systems for Stoichiometric Natural Gas Engines

Development of an Ammonia Reduction Aftertreatment Systems for Stoichiometric Natural Gas Engines

Modeling the Effect of Nonuniformities from Urea Injection on SCR Performance Using CFD

Development and validation of a model for wall-flow type selective catalytic reduction system

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