Kinetic modeling of the total oxidation of propane over CuO-CeO2/γ-Al2O3

The total oxidation of propane is studied by means of steady-state experiments over a CuO-CeO2/gamma Al2O3 catalyst at propane inlet partial pressures of 0.2-1.0 kPa, oxygen inlet partial pressures of 2.7-27.6 kPa and temperatures from 543 to 648 K. The inlet ratio of oxygen to propane is varied between 6.1 and 28.0 mol(02),(0) mol(c3H8.0)(-1). Water and carbon dioxide inlet partial pressures up to 12.4 kPa are investigated. The complete experimental dataset was regressed with a priori possible Langmuir-Hinshelwood (LH), Eley-Rideal (ER) and Mars-van Krevelen (MVK) rate equations. A LH rate equation, the rate-determining step being the surface reaction between one adsorbed propane species and one dissociatively adsorbed oxygen species, allows the best description of the data. The surface reaction activation energy amounts to 74.4 +/- 4.6 kJ mol(-1). All adsorption steps in the selected reaction mechanism are quasi-equilibrated. The values of the preexponential factors of the adsorption equilibrium coefficients correspond to rather mobile surface species. Molecular water adsorption is followed by a dissociation of the adsorbed water by interaction with a dissociatively adsorbed oxygen species to form two hydroxyl species. (C) 2009 Elsevier B.V. All rights reserved.