NH sub(3) formation over a lean NOx trap (LNT) system: Effects of lean/rich cycle timing and temperature

A commercial lean NO[subx] trap (LNT) catalyst containing Pt, Pd, Rh, BaO, and CeO[sub 2] was evaluated in this investigation. The effects of lean/rich cycle timing on the NO[subx], CO and C[sub 3]H[sub 6] conversions and on the NH[sub 3] and N[sub 2]O selectivities were considered. Two distinct lea...

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Bibliographic Details
Published in:Applied catalysis. B, Environmental Environmental, 2014-04, Vol.147, p.698-710
Main Authors: DiGiulio, Christopher D, Pihl, Josh A, Choi, Jae-Soon, Parks, James E, Lance, Michael J, Toops, Todd J, Amiridis, Michael D
Format: Article
Language:English
Subjects:
Carbon monoxide
Catalysis
Conversion
Cycles
Palladium
Platinum
Selectivity
Time measurements
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Summary:A commercial lean NO[subx] trap (LNT) catalyst containing Pt, Pd, Rh, BaO, and CeO[sub 2] was evaluated in this investigation. The effects of lean/rich cycle timing on the NO[subx], CO and C[sub 3]H[sub 6] conversions and on the NH[sub 3] and N[sub 2]O selectivities were considered. Two distinct lean/rich cycling regimes were identified. At low temperatures, NO[subx] release and reduction were relatively slow processes. As a result, a longer, lower-concentration rich dose favored increased cycle averaged NO[subx] conversions. For example, extending the rich period from 5 to 15 s at 250 [degrees]C, while holding the overall reductant dose constant, resulted in an increase in cycle averaged NO[subx] conversion from 59 to 87%. At high temperatures, the opposite was found to be true.
ISSN:0926-3373
DOI:10.1016/j.apcatb.2013.09.012