Removal of nitrogen oxides from the exhaust of a lean-tune gasoline engine

Bögner, W.; Kramer, Michael J.; Krutzsch, B.; Pischinger, Stefan; Voigtländer, D.; Wenninger, G.; Wirbeleit, F.; Brogan, Mark S.; Brisley, R. J.; Webster, Dennis

doi:10.1016/0926-3373(95)00035-6

Cited by 195 publications

(88 citation statements)

References 16 publications

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“…In this way, the catalyst is regenerated before going through another lean-rich cycle. This successive cycling operation can provide high NO x removal efficiency [5,6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Wang

2010

Applied Catalysis B: Environmental

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a b s t r a c tA comparative study of Pt/Ba/Al 2 O 3 , Co/Ba/Al 2 O 3 , Pt/Co/Al 2 O 3 and Pt/Co/Ba/Al 2 O 3 was performed in regards to their NO x storage capacities and NO oxidation abilities as a function of temperature. The nitrate stability and dynamic behaviors of NO x storage reduction during lean/rich fuel cycles using hydrogen as a reductant were also investigated over these catalysts. It was found that Pt/Co/Ba/Al 2 O 3 possessed the largest NO x storage capacity within the temperature range of 200-350 • C. The existence of Co not only improved the oxidation of NO to NO 2 under lean conditions, but also enhanced the release and reduction of NO x during the rich phase. The Pt and Co co-supported catalysts showed better NO x storage reduction activity and higher N 2 selectivity than Pt supported Ba/Al 2 O 3 catalysts within the tested temperature range. As for Pt/Co/Ba/Al 2 O 3 , high conversion was obtained at either a low reductant concentration with long duration time or a high reductant concentration with short duration time during the rich phase. In situ FTIR studies showed that NO x adsorption over Co-containing catalysts takes "nitrite route" as an important pathway. The intimate contact of Co and Ba/Al could accelerate nitrite/nitrate formation and the synergistic effect of Pt and Co could accelerate NO x reduction.

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“…In this way, the catalyst is regenerated before going through another lean-rich cycle. This successive cycling operation can provide high NO x removal efficiency [5,6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Wang

2010

Applied Catalysis B: Environmental

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“…Among the different strategies to reduce NO x -emissions, the NO x storage-reduction (NSR) catalyst system is wellestablished because of its high lean DeNO x activity combined with a suitable durability and three-way catalyst activity [2,5,6].…”

Section: Introductionmentioning

confidence: 99%

“…NSR catalysts consist of precious metals (Pt, Rh) for the oxidation of NO to NO 2 (under lean fuel conditions) and reduction of NO x (under rich conditions), and of a storage component deposited on carrier oxides with a high surface area, such as La 2 O 3 -stabilized γ-Al 2 O 3 or CeO 2 [5][6][7][8][9][10]. Typical NO x storage compounds are alkali metal oxides or alkaline-earth metal oxides like potassium oxide or barium oxide.…”

Section: Introductionmentioning

confidence: 99%

Formation and stability of barium aluminate and cerate in NOx storage-reduction catalysts

Casapu

Grunwaldt

Maciejewski

et al. 2006

Applied Catalysis B: Environmental

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The formation and stability of BaAl 2 O 4 and BaCeO 3 in Pt-Ba/Al 2 O 3 and Pt-Ba/CeO 2 based NO x storage-reduction (NSR) catalyst has been investigated using kinetic measurements, X-ray diffraction, thermal analysis and X-ray absorption spectroscopy. In as-prepared state, the Ba-component in the NSR catalysts was made up of amorphous BaO and BaCO 3 . The formation of BaAl 2 O 4 started above 850°C, whereas the formation of BaCeO 3 was already observed at 800°C and was faster than that of BaAl 2 O 4 . The stability of BaAl 2 O 4 and BaCeO 3 in various liquid and gaseous atmospheres was different. BaAl 2 O 4 was rapidly hydrated at room temperature in the presence of water and transformed to Ba(NO 3 ) 2 and γ-alumina in the presence of HNO 3 , whereas BaCeO 3 was decomposed to much lower extent under these conditions. Interestingly, BaCeO 3 was transformed to Ba(NO 3 ) 2 /CeO 2 in the presence of NO 2 /H 2 O at 300 -500 °C. Also the presence of CO 2 led to decomposition of barium cerate, which has important consequences for the catalyst ageing under NO x -storage conditions and can be exploited for regeneration of thermally aged NSR-catalysts.

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“…In this context, at the end of the 1980s we developed a new concept to remove NOx from oxidative exhaust gas from lean-burn engines, the so-called NOx storage and reduction (NSR) catalyst system. The system is currently being improved as one of the most feasible and attractive solutions to this technical challenge 7), 8) . The NSR catalyst system was first applied in practice for a port-injection gasoline lean-burn engine in 1994 7), 9) , and then improved and applied for a directinjection gasoline lean-burn engine in 1997 10) .…”

Section: Introductionmentioning

confidence: 99%

Improvement of Catalysts for NO<sub><i>x</i></sub> Storage and Reduction for Gasoline-fueled Automotive Exhaust

Takahashi

Imagawa

2009

J. Jpn. Petrol. Inst.

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Catalysts for nitrogen oxide (NOx) storage and reduction oxidize nitrogen monoxide (NO) emitted from auto motive lean-burn engines to nitrogen dioxide (NO2) that is then stored on doped NOx storage materials such as barium and/or potassium compounds as nitrate ions (NO3 -). In a reducing atmosphere provided by a suitable engine management system, the nitrates formed are subsequently reduced and decomposed into NOx via reactions between reducing agents in the exhaust gas such as hydrogen, carbon monoxide and hydrocarbons. The emitted NOx is finally reduced and detoxified to nitrogen. To meet stringent emission regulations for automotive exhaust pollutants, NOx storage and reduction catalysts must have excellent NOx removal activity and an extremely long lifetime. These catalysts can deteriorate not only due to thermal stress, but also to sulfur poisoning. Thermal stress causes a decrease in the number of active sites through sintering of precious metals, decreases the specific surface area of the support and leads to solid-phase reaction between the NOx storage material and the support. Sulfur is present in exhaust gas derived from gasoline fuel and it competes with NOx for storage and reacts with the doped NOx storage material to form sulfates. Once NOx storage materials are sulfated, they drastically lose their NOx storage capability. This report reviews the technologies used to overcome these issues and to improve the durability of NOx storage and reduction catalysts against both thermal damage and sulfur poisoning. An advanced novel catalyst system for NOx removal with synergistic NOx storage and reduction with ammonia (NH3) formation, storage and NOx selective reduction by NH3 functions is also described.

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Removal of nitrogen oxides from the exhaust of a lean-tune gasoline engine

Cited by 195 publications

References 16 publications

Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Effect of Co addition to Pt/Ba/Al2O3 system for NOx storage and reduction

Formation and stability of barium aluminate and cerate in NOx storage-reduction catalysts

Improvement of Catalysts for NO<sub><i>x</i></sub> Storage and Reduction for Gasoline-fueled Automotive Exhaust

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