Development of a Global Kinetic Model for a Commercial Lean NOx Trap Automotive Catalyst Based on Laboratory Measurements

Modeling NOx Storage and Reduction for a Diesel Automotive Catalyst Based on Synthetic Gas Bench Experiments

“…The delayed ammonia slip, with respect to other species, suggests a pathway through which ammonia is generated from the reaction of primary reductants with stored NO x. The ammonia is further consumed as a secondary reductant to reduce remaining stored NO x to N 2 , where NO x or N 2 O result as products; this assumption is coherent with the models proposed by Shwan et al, 27 Kocǐ ́et al, 26,29 and Rafigh et al 21 The calibration is performed, moving from lower temperatures to higher temperatures, using Arrhenius rate functions, step by step as follows:…”

“…The reactions in this step include the storage of oxygen on ceria sites during lean phase and the reduction of stored oxygen by means of CO during rich phase, more details regarding the kinetic scheme can be found in. 21 Moreover, H 2 and HCs are also capable to consume the stored oxygen.…”

“…Oxygen storage on ceria is modeled using an equilibrium function, which takes into account the increased storage capacity, as a function of temperature and limited by a maximum storage equilibrium curve. 21 Calibration of WGS can be performed by taking into account the OSC experimental tests. At the beginning of the rich phase of the test, the produced H 2 can be consumed reacting with oxygen molecules stored on ceria.…”

“…In order to take into account the nonmonotonic storage capacity of Ba sites, with respect to temperature, a multiple-adsorption site model was considered, 8,25 including three types of Ba sites, which differ in the active site density. 21 Even if pure adsorption/ desorption test procedures were not available to detect if multiple temperature-dependent storage sites were present on the analyzed component, it was observed that multiple sites must be taken into account on the modeling side to properly model the LNT storage capacity. In particular, it was observed that, for temperatures of <210 °C, two types of Ba sites are sufficient, while, at higher temperatures, the third type of Ba site is activated, which is inhibited by NO at lower temperatures with a function G defined as given in eq 9:…”

Composition/Performance Evaluation of Lean NOx Trap Catalysts for Coupling with SCR Technology

“…Publications concerning the performance of fully formulated LNT systems mainly deal with operating strategies, [55] aging and poisoning effects, [56,57,58,59] the influence of cycling conditions on NO x conversion and selectivity of product gas components [60,61] as well as kinetic modeling [62] for single LNT operation. However, these studies do not examine the required LNT performance for coupling with SCR catalysts.…”