Determination of the NOx Loading of an Automotive Lean NOx Trap by Directly Monitoring the Electrical Properties of the Catalyst Material Itself

Fremerey, Peter; Reiß, Sebastian; Geupel, Andrea; Fischerauer, Gerhard; Moos, Ralf

doi:10.3390/s110908261

Cited by 36 publications

(24 citation statements)

References 41 publications

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“…For example, it can be used to monitor the state of selective catalytic reduction (SCR) catalysts (NH 3 -storage) [11,12], three way catalysts (oxygen loading) [13], or lean NO x traps (NO x loading or state of regeneration) [14]. Overviews are given in the reviews [15,16].…”

Section: Fundamentalsmentioning

confidence: 99%

Influencing Parameters on the Microwave-Based Soot Load Determination of Diesel Particulate Filters

et al. 2016

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Diesel Particulate Filters (DPF) are an essential part of today's diesel exhaust gas aftertreatment systems. For an effective filter regeneration strategy, the precise knowledge of the actual trapped soot mass is essential. Besides the state-of-the-art technology of determining the soot load via pressure drop and/or model-based, a microwave-based method enables direct and in situ soot load detection. Thereby, an electric field is impressed into the filter housing and the power transmission is measured, which correlates with the soot load. In this study, influencing parameters, especially temperature and humidity, are examined and compared to the sensitivity towards soot accumulation. Measurements were conducted in a laboratory test bench with a filter-core, which had been previously loaded with soot in an engine dynamometer. While humidity does not have a notable effect, the influence of temperature needs to be considered for real world application. Finally, a complete filter regeneration of the DPFcore in the laboratory test bench could be monitored with the microwave-based system. The carbon balance-derived burned soot mass coincides very well with the microwave derived transmission parameter.

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Section: Fundamentalsmentioning

confidence: 99%

Influencing Parameters on the Microwave-Based Soot Load Determination of Diesel Particulate Filters

et al. 2016

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“…Typical applications are the determination of the oxygen loading of three-way catalytic converters (Moos et al, 2008Beulertz et al, 2013;Reiß et al, 2011a), or the soot loading (Sappok et al, 2010;Feulner et al, 2013) or ash loading (Kulkarni et al, 2013) of fullsized diesel particulate filters. The storage degree of NO in lean NO x traps (Fremerey et al, 2011;Moos et al, 2009) and the NH 3 loading on SCR catalyst devices have also been successfully monitored (Reiß et al, 2011b;Rauch et al, 2014Rauch et al, , 2015 using the cavity perturbation method.…”

Section: Introductionmentioning

confidence: 99%

Ammonia storage studies on H-ZSM-5 zeolites by microwave cavity perturbation: correlation of dielectric properties with ammonia storage

Dietrich

Rauch

Simon

et al. 2015

J. Sens. Sens. Syst.

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Abstract.To meet today's emission standards, the ammonia-based selective catalytic reduction (SCR) has become the major NO x control strategy for light and heavy diesel engines. Before NO x reduction can proceed, adsorption of ammonia on the acidic sites of the catalyst is necessary. For improvements in efficiency and control of the exhaust gas aftertreatment, a better understanding of the ammonia storage on the acidic sites of zeolite-based SCR catalysts is needed. Thereby, the correlation of dielectric properties of the catalyst material itself with the ammonia storage is a promising approach. Recently, a laboratory setup using microwave cavity perturbation to measure the dielectric properties of catalyst material has been described. This study shows the first experimental data on zeolite-based SCR materials in their H-form. The SCR powder samples are monitored by microwave cavity perturbation while storing and depleting ammonia, both with and without admixed NO x at different temperatures. Its complex dielectric permittivity is found to correlate closely with the stored mass of ammonia. The influence of the temperature and the Si / Al ratio of the zeolite to the ammonia storage behavior are also examined. These measurements disclose different temperature dependencies and differing sensitivities to ammonia storage for both real and imaginary parts of the complex permittivity. The apparent constant sensitivity of the real part can be related to the polarity of the adsorbed ammonia molecules, whereas the imaginary part depends on the Si / Al ratio and is related to the conductivity mechanisms of the zeolite material by proton hopping. It provides information about the zeolite structure and the number of (and the distance between) acidic storage sites, in addition to the stored ammonia mass.

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“…Their frequencies, the resonance frequencies f res , depend on the electrical properties of the resonator filling. This has been extensively shown for three-way catalysts [40,41], for lean NO x traps [42,43], for diesel particulate filters [44,45] and for a zeolite-based SCR catalyst [46]. As the conductivity of the catalyst material increases due to the adsorption of ammonia (see Fig.…”

Section: Experimental Setups and Preliminary Testsmentioning

confidence: 92%

A microwave-based method to monitor the ammonia loading of a vanadia-based SCR catalyst

Rauch¹,

Albrecht²,

Kubinski³

et al. 2015

Applied Catalysis B: Environmental

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Determination of the NOx Loading of an Automotive Lean NOx Trap by Directly Monitoring the Electrical Properties of the Catalyst Material Itself

Cited by 36 publications

References 41 publications

Influencing Parameters on the Microwave-Based Soot Load Determination of Diesel Particulate Filters

Influencing Parameters on the Microwave-Based Soot Load Determination of Diesel Particulate Filters

Ammonia storage studies on H-ZSM-5 zeolites by microwave cavity perturbation: correlation of dielectric properties with ammonia storage

A microwave-based method to monitor the ammonia loading of a vanadia-based SCR catalyst

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