Detailed kinetic modeling of NOxNOx storage and reduction with hydrogen as the reducing agent and in the presence of CO2 and H2O over a Pt/Ba/Al catalyst

Lindholm, Anna Maria; Currier, Neal W.; Li, Junhui; Yezerets, Aleksey; Olsson, Louise

doi:10.1016/j.jcat.2008.06.022

Cited by 66 publications

(55 citation statements)

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“…Most recently, people place more emphases on the mechanism study of NO x storage and reduction. Several kinetic models were developed to predict evolution of the effluent gases as well as surface species either in trapping processes or in lean/rich cycles [22][23][24][25][26]. Considering the complexities of catalyst components and multi-step reactions of this system, many aspects of Pt/Ba/Al 2 O 3 still require improvement and clarification, including NO x storage capacity, reduction efficiency, and low temperature performances.…”

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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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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“…However, because our reactor model does not include surface transport of reactive species, the effects of such transport must be regarded as being lumped into the corresponding rate constants. A reaction somewhat similar to (S35) is used in Lindholm et al (2008). The same reference postulates a number of spillover reactions for the reduction of stored NO x , but these are far from elementary.…”

Section: Reaction Mechanismmentioning

confidence: 99%

“…These include simple control-oriented models (Ketfi-Cherif et al, 2000;Kim et al, 2003;Larsson et al, 1999), global kinetic models (Bhatia et al, 2009;Guthenke et al, 2007;Koci et al, 2004;Koci et al, 2009;Koop and Deutschmann, 2007;Laurent et al, 2003;Olsson et al, 2005), and models attempting a detailed description of the surface chemistry (Lindholm et al, 2008;Olsson et al, 2001;Olsson et al, 2002;Xu et al, 2008). It is no longer practical to give a brief survey of this growing field, which is the subject of a recent comprehensive review (Roy and Baiker, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…This was due to the fact that storage in this model was limited by NO oxidation to NO 2 . Lindholm et al (2008) have removed this limitation by assuming that NO can be directly adsorbed on both BaCO 3 and unidentified S 3 sites. Their rate equations suggest that NO adsorbs on both of these sites without the assistance of either a noble metal or gas phase oxygen.…”

Section: Introductionmentioning

confidence: 99%

“…Unlike the storage mechanism, the regeneration mechanism proposed by Lindholm et al (2008) is highly globalized, with reactions involving as many as twelve reactant molecules. Needless to say, this makes the assignment of reaction orders highly problematic.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of lean NOx trap performance with microkinetic chemistry and without mass transfer.

Larson¹,

Daw

Pihl

et al. 2011

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A microkinetic chemical reaction mechanism capable of describing both the storage and regeneration processes in a fully formulated lean NO x trap (LNT) is presented. The mechanism includes steps occurring on the precious metal, barium oxide (NO x storage), and cerium oxide (oxygen storage) sites of the catalyst. The complete reaction set is used in conjunction with a transient plug flow reactor code to simulate not only conventional storage/regeneration cycles with a CO/H 2 reductant, but also steady flow temperature sweep experiments that were previously analyzed with just a precious metal mechanism and a steady state code. The results show that NO x storage is not negligible during some of the temperature ramps, necessitating a re-evaluation of the precious metal kinetic parameters. The parameters for the entire mechanism are inferred by finding the best overall fit to the complete set of experiments. Rigorous thermodynamic consistency is enforced for parallel reaction pathways and with respect to known data for all of the gas phase species involved. It is found that, with a few minor exceptions, all of the basic experimental observations can be reproduced with these purely kinetic simulations, i.e., without including mass-transfer limitations. In addition to accounting for normal cycling behavior, the final mechanism should provide a starting point for the description of further LNT phenomena such as desulfation and the role of alternative reductants. 4 ACKNOWLEDGMENTSThe authors thank Dr. Andrew E. Lutz, formerly of Sandia, for initial development of the Chemkin-based transient plug flow reactor code (TPLUG). The efforts at Oak Ridge were sponsored by the U.S.

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A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al₂O₃

et al. 2013

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A global kinetic model which describes H 2 -assisted NH 3 -SCR over an Ag/Al 2 O 3 monolith catalyst has been developed. The intention is that the model can be applied for dosing NH 3 and H 2 to an Ag/Al 2 O 3 catalyst in a real automotive application as well as contribute to an increased understanding of the reaction mechanism for NH 3 -SCR. Therefore, the model needs to be simple and accurately predict the conversion of NO x . The reduction of NO is described by a global reaction, with a molar stoichiometry between NO, NH 3 and H 2 of 1:1:2. Further reactions included in the model are the oxidation of NH 3 to N 2 and NO, oxidation of H 2 , and the adsorption and desorption of NH 3 . The model was fitted to the results of an NH 3 -TPD experiment, an NH 3 oxidation experiment, and a series of H 2 -assisted NH 3 -SCR steady-state experiments. The model predicts the conversion of NO x well even during transient experiments. V C 2013 American Institute of Chemical Engineers AIChE J, 59: [4325][4326][4327][4328][4329][4330][4331][4332][4333] 2013

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Detailed kinetic modeling of NOxNOx storage and reduction with hydrogen as the reducing agent and in the presence of CO2 and H2O over a Pt/Ba/Al catalyst

Cited by 66 publications

References 49 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

Simulation of lean NOx trap performance with microkinetic chemistry and without mass transfer.

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al₂O₃

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Detailed kinetic modeling of NOxNOx storage and reduction with hydrogen as the reducing agent and in the presence of CO2 and H2O over a Pt/Ba/Al catalyst

Cited by 66 publications

References 49 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

Simulation of lean NOx trap performance with microkinetic chemistry and without mass transfer.

A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al2O3

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Product

Resources

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A kinetic model of the hydrogen assisted selective catalytic reduction of NO with ammonia over Ag/Al₂O₃