A Laboratory Study of NOX Reduction During the Rich Operating Period Over a NOX Storage Catalyst 1999-01-3502
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).
Citation: Fendeleur, S., Pope, C., Mahzoul, H., Brilhac, J. et al., "A Laboratory Study of NOX Reduction During the Rich Operating Period Over a NOX Storage Catalyst," SAE Technical Paper 1999-01-3502, 1999, https://doi.org/10.4271/1999-01-3502. Download Citation
Author(s):
S. Fendeleur, C. Pope, H. Mahzoul, J-F. Brilhac, P. Gilot, G. Prado, M. Guyon, B. R. Stanmore
Affiliated:
Université de Haute Alsace, Renault S.A., University of Queensland
Pages: 7
Event:
International Fuels & Lubricants Meeting & Exposition
ISSN:
0148-7191
e-ISSN:
2688-3627
Also in:
Gasoline Direct Injection and Diesel Aftertreatment-SP-1476, SAE 1999 Transactions - Journal of Fuels and Lubricants-V108-4
Related Topics:
Nitrogen oxides
Catalysts
Storage
Gases
Metals
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