Steady state and lean-rich cycling study of a three-way NOX storage catalyst: Modeling

Li, Mengmeng; Malamis, Sotirios A.; Epling, William S.; Harold, Michael P.

doi:10.1016/j.apcatb.2018.09.094

Cited by 14 publications

(13 citation statements)

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“…And G is the inhibition factor. The inhibition factor has been proved as an efficient way to include competition for active sites for global reaction models by many previous works [14,15,21]. The design of inhibition factors for major reactions are discussed in the following arguments.…”

Section: Model Descriptionmentioning

confidence: 99%

“…For reaction 2 (CO oxidation reaction), two species inhibition coefficients are included in the reaction rate formulation, CO self-inhibition and NO inhibition. CO self-inhibition effect is a known phenomenon [22] and is usually modeled by a second order inhibition factor [14,21]. NO competes for active Pd/Rh sites with O 2 and the competition has been modeled with a 0.7 order inhibition factor [14].…”

Section: Model Descriptionmentioning

confidence: 99%

“…CO self-inhibition effect is a known phenomenon [22] and is usually modeled by a second order inhibition factor [14,21]. NO competes for active Pd/Rh sites with O 2 and the competition has been modeled with a 0.7 order inhibition factor [14]. The adsorption and activation of CH 4 is notoriously difficult.…”

Section: Model Descriptionmentioning

confidence: 99%

“…The same NO/O 2 competition also affects oxidation of C 2 H 6 and CH 4 , therefore these reactions inherit same formulation of NO inhibition factor. In addition, for hydrocarbons, there is a competition for absorption sited with CO, which has been mostly modeled by a second order inhibition [14,21,23]. While NMHCs have high conversion rate under lean conditions, methane conversion is limited under oxygen abundance conditions.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Global reaction models simplify the elementary steps to global reactions and saves computational power. Global reaction models are widely implemented to predict catalyst conversion behaviors in steady and transient feed of gasoline [14] and natural gas exhausts [15].…”

mentioning

confidence: 99%

See 4 more Smart Citations

Modeling of Three Way Catalyst Behavior Under Steady and Transient Operations in a Stoichiometric Natural Gas Fueled Engine

Wang¹,

Eggenschwiler²

2021

SAE Technical Paper Series

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Methane abatement in the exhaust gas of natural gas engines is much more challenging in respect to the oxidation of other higher order hydrocarbons. Under steady state λ sweep, the methane conversion efficiency is high at exact stoichiometric, and decreases steeply under both slightly rich and slightly lean conditions. Transient lean to rich transitions can improve methane conversion at the rich side. Previous experimental work has attributed the enhanced methane conversion to activation of methane steam reforming. The steam reforming rate, however, attenuates over time and the methane conversion rate gradually converges to the low steady state values. In this work, a reactor model is established to predict steady state and transient transition characteristics of a three-way catalyst (TWC) mounted in the exhaust of a natural gas heavy-duty engine. In total 17 global reactions are selected and implemented in the reactor model, including oxidation reactions, NO x related reactions, water gas shift and steam reforming, and ceria oxygen storage related reactions. Inhibition factors are introduced to model the competition of different species for active sites. To model the transient enhancement of methane conversion, an activation and deactivation mechanism of methane steam reforming based on active ceria sites is proposed and developed. Both lean to rich and rich to lean λ transitions are simulated and compared with engine experiment results. The proposed model captures key characteristic behaviors of the TWC in both steady state λ sweep and transient λ transitions. The results provide insights in TWC reaction mechanisms at near stoichiometric operation and can be used as a starting point to predict the effect of dedicated control strategies.

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Section: Model Descriptionmentioning

confidence: 99%