Global Kinetic Modeling and Analysis of Lean NO<inf>x</inf> Traps (LNT) Catalysts

Lean NOx traps (LNT) is an after-treatment technique that is used for NOx abatement in lean-burn engines. The objective of this work is to develop a generic kinetic model applicable to various LNT catalyst formulations and to apply it to the design and analysis of the LNT reactor. The kinetic model of 16 reactions is proposed using Langmuir-Hinshelwood kinetics. It is validated against experiments reported in the literature, performed for a family of catalyst formulations that use Pt-group metals as the active catalyst and barium-based NOx storage, and is capable of predicting the performance with minimal modification of parameters. A kinetic analysis highlights the contribution of each reaction to the overall kinetic scheme in order to determine the important steps and qualitatively validate the model. A reactor-level analysis is done by varying the operating conditions and the time scales of the lean and rich phases are optimized.