Micro-kinetics of NOx storage and reduction with H2/CO/C3H6 on Pt/BaO/Al2O3 monolith catalysts

Isothermal steady state NO storage and reduction on Pt/BaO/Al2O3 by H-2/CO/C3H6 reactant mixtures is studied using, 1 + 1 dimensional two-phase model that accounts for washcoat diffusional limitations. It predicts the storage and reduction performance over a wide range of inlet feed concentrations and temperatures. A major limitation of global kinetic models is not being able to predict accurately the performance of the catalyst with changing feed composition. Micro-kinetic models elucidating the role of individual reductants can account for such variations. The temperature dependence of the rate constants has been quantified so that the surface chemistry is consistent with experimental observations. Inclusion of washcoat diffusion enables the model to accurately predict the NOx conversion and zscale-up performance of the catalyst over a wide temperature range. The sensitivity of the estimated kinetic parameters to the effective diffusivities in the washcoat is analyzed. Results indicate that the estimated micro-kinetic parameters are influenced by the washcoat pore structure as well as the properties of the catalytic and storage components. (C) 2014 Elsevier B.V. All rights reserved.