Kinetic Modeling of Dynamic Aspects of the Standard NH₃-SCR Reaction Over V₂O₅-WO₃/TiO₂and Fe-Zeolite Commercial Catalysts for the Aftertreatment of Diesel Engines Exhausts

Abstract

Résumé -Modélisation cinétique d'aspects dynamiques de la réaction de RCS-NH 3 standard sur des catalyseurs commerciaux V 2 O 5 -WO 3 /TiO 2 et Fe-zéolite pour le post-traitement de gaz d'échappement de moteurs Diesel -Les données cinétiques dynamiques recueillies sur des catalyseurs V 2 O 5 -WO 3 /TiO 2 et Fe-zéolite commerciaux en analysant le RCS-NH 3 standard du NO pour la réduction des NO x des gaz d'échappement de véhicules ont montré des effets transitoires à basse température, liés à l'action inhibitrice d'ammoniac en excès. Afin de décrire de tels effets transitoires, une expression de la vitesse spécifique prenant en compte l'inhibition par NH 3 de la réaction de RCS standard est nécessaire pour des modèles mathématiques de convertisseurs par RCS réels. Nous présentons ici une équation de vitesse de type Mars-Van Krevelen à double site pour décrire les caractéristiques dynamiques associées à l'injection et à l'arrêt de l'ammoniac sur des catalyseurs à la fois à base de V et Fe-zéolite. Abstract

Development of a Nonequilibrium Multisite Kinetic Model for NH3-SCR of NOx on CHA Cu-SAPO-34: Impact of Active Site Configurations and Locations

“…Therefore, the current model is assumed to depict the nitrite formation on copper cations as a key step for STD SCR in wet conditions. The reactions eqs , – implemented in the model are in line with previous mechanistic studies implying water in SCR process and further employed in various model constructions. , Finally, this inhibition effect further demonstrates that an optimized surface coverage from NH 3 is required for a maximized NO conversion in N 2 . Note that similar H 2 O desorption activation energies to those given in Supporting Information Table S5 were estimated on strong active copper species as demonstrated by Olsson et al during previous model construction studies dedicated to the impacts of water and NH 3 on zeolite catalyst …”

“…38,71 Finally, this inhibition effect further demonstrates that an optimized surface coverage from NH 3 is required for a maximized NO conversion in N 2 . 110 Note that similar H 2 O desorption activation energies to those given in Supporting Information Table S5 were estimated on strong active copper species as demonstrated by Olsson et al during previous model construction studies dedicated to the impacts of water and NH 3 on zeolite catalyst. 54 In that respect, as observed at low temperatures within 200 and 300 °C between Figures 5B and 7B , it is S3 which adequately represents the main active species.…”

Nonlinear model predictive control applied to multivariable thermal and chemical control of selective catalytic reduction aftertreatment

“…In operation, this maximum storage is not achieved, since the reaction rates determine the storage level. 17 For adsorption, the reaction rate is given by…”

Ammonia CI engine aftertreatment systems design and flow simulation

“…Depending on materials used, residence time (resultant of length and flow velocity) and temperature different mechanism becomes more pronounced. Among those Eley-Rideal of surface-only reaction, 2 cyclecatalysis Topsøe [13] catalysis model for standard reaction time, Ciardelli [14] or Nova [15] for low temperature NO x reduction and Grossal for NH 4 NO 3 formation are commonly used. Calculations run those mechanisms in parallel [13] or even coupled as in Mars-Van Krevelen model [15] when process is heterogynous or one of them when it's possible to select one homogenous leading mechanism.…”