Modelling of the kinetics of the catalytic soot oxidation on Fe2O3

This paper addresses the kinetic modelling of the soot oxidation on a Fe2O3 model catalyst. The kinetics was evaluated by temperature programmed oxidation using a packed bed of tight contact mixtures of Fe2O3 and soot. The reaction rate was expressed by a global-kinetic approach taken from a previous paper. Some kinetic parameters were determined by a fit to experimental TPO data using a stationary 1-D CSTR model with coupled mass and heat balance. The fitting led to an apparent activation energy of 73 kJ/mol, while the pre-exponential factor was calculated to be 1.6 × 103 m3/(mol s). The kinetic model was validated by simulations and was then implemented into a transient 2-D model of the fixed-bed reactor. This model implied the conservation of mass, heat and momentum and was checked by temperature measurements conducted with an IR camera. Finally, the 2-D model was validated by simulating some TPO investigations. The simulations provide local concentrations of CO2, O2 and soot as well as local temperature and gas velocity. Particularly, these results suggest the absence of any drastic gradients of concentration and temperature in the packed bed due to the convection of the gas stream.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Fe2O3 model catalyst was used for the modelling of the kinetics of soot oxidation. ► A stationary 1-D and a transient 2-D model was developed and validated by simulations. ► The gradients of concentrations of gas species as well as solid soot are driven by the fluid dynamics. ► No hot spots and drastic concentration gradients appear due to convective mass transport.