A Laboratory Study of NOX Reduction During the Rich Operating Period Over a NOX Storage Catalyst

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A Laboratory Study of NOX Reduction During the Rich Operating Period Over a NOX Storage Catalyst

Stanmore, B. R. / Pope, C. / Prado, G. / Mahzoul, H. / Brilhac, J-F. / Guyon, M. / Gilot, P. / Fendeleur, S.

The behaviour of a NOx storage catalyst in powdered form and containing a storage component based on alkaline metal was investigated under rich conditions. Experiments were conducted in a fixed-bed flow reactor with the space velocity set at 45,000 h-1.From these experiments it was possible to extract the fractional NOx reduction and the efficiency of use of the reductant. With 0.9% CO as a reductant at 350°C, complete utilisation of CO was achieved up to 70% NOx conversion as treatment time was increased. To obtain 90% NOx conversion required longer times, and 23% of the CO did not participate in the reduction of NOX. A reductant balance shows that about 40% of the CO added is used to reduce the catalyst surface when the flow is switched from lean to rich.The ranking of efficiencies of different reductant gases at 350°C gave the following sequence: 0.9% H2 ≈ 0.9% CO > 1285 ppm toluene > 3000 ppm propene ≈ 1125 ppm i-octane > 3000 ppm propane. Thus in an actual exhaust the NOx reduction is due mainly to H2 and CO. A study of the effect of temperature showed that maximum efficiency is obtained in the range 350 to 400°C. A study of the effect of concentration showed that for the injection of a given mass of reductant (CO), it is better to use a shorter burst at higher concentration. The competition for reductant between the NOx coming from nitrate decomposition and that needed for catalyst reduction requires a 3:1 excess (i.e. an approximate ratio of two between the quantity of reductant injected and the amount of NOX adsorbed during lean phase operations).

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Dokumentinformationen

Titel :

A Laboratory Study of NOX Reduction During the Rich Operating Period Over a NOX Storage Catalyst

Weitere Titelangaben:

Sae Technical Papers

Beteiligte:

Stanmore, B. R. (Autor:in) / Pope, C. (Autor:in) / Prado, G. (Autor:in) / Mahzoul, H. (Autor:in) / Brilhac, J-F. (Autor:in) / Guyon, M. (Autor:in) / Gilot, P. (Autor:in) / Fendeleur, S. (Autor:in)

Kongress:

International Fuels & Lubricants Meeting & Exposition ; 1999

Erschienen in:

Sae Technical Paper Series

Erscheinungsdatum :

1999-10-25

ISSN :

2688-3627 , 0148-7191

DOI :

https://doi.org/10.4271/1999-01-3502

Medientyp :

Aufsatz (Konferenz)