Mean field modeling of NO oxidation over Pt/Al2O3 catalyst under oxygen-rich conditions

Abstract This paper deals with catalytic NO oxidation into NO 2 over Pt/Al 2 O 3 in oxygen-rich exhaust. Based upon kinetic measurements performed in a gradient free loop reactor and DRIFTS examinations, a mean field model is established to simulate catalytic data and calculate surface coverages. The kinetic model includes a network of 16 elementary reactions whereby NO oxidation is described by an Eley–Rideal-type mechanism. A comparison of measured and simulated data shows that the experimental results of the NO/O 2 reaction are well described by the model. Kinetic parameters for the elementary reactions were taken from the literature or determined from a fit of the model to experimental data. To reduce the number of free parameters, we estimated the activation energy of O desorption for zero coverage and the corresponding linear constant α 2 by numerically simulating the O 2 TPD pattern. For the kinetic model of NO oxidation, the preexponential factors for NO 2 adsorption (68 m 3  s −1  m −2 ) and NO oxidation (104 m 3  s −1  m −2 ); the activation energies for NO desorption (114 kJ mol −1 ), NO 2 desorption (72 kJ mol −1 ), NO oxidation (35 kJ mol −1 ), and NO 2 dissociation (51 kJ mol −1 ); and the linear constant α 13 (14 kJ mol −1 ) are fitted. Furthermore, the calculated surface coverages provide evidence for the effect of CO, CO 2 , and H 2 O on the rate of NO oxidation.