Kinetic modeling of oxidative dehydrogenation of propane with CO₂ over MoO_x/La₂O₃–Al₂O₃ in a fluidized bed

Abstract

A 4‐step kinetic model of CO2‐assisted oxidative dehydrogenation (ODH) of propane to C2/C3 olefins over a novel MoOx/La2O3–γAl2O3 catalyst was developed. Kinetic experiments were conducted in a CREC Riser Simulator at various reaction temperatures (525–600 °C) and times (15–30 s). The catalyst was highly selective towards propylene at all combinations of the reaction conditions. Langmuir‐Hinshelwood type kinetics were formulated considering propane ODH, uni‐ and bimolecular cracking of propane to produce a C1‐C2 species. It was found that the one site type model adequately fitted the experimental data. The activation energy for the formation of propylene (67.8 kJ/mol) is much lower than that of bimolecular conversion of propane to ethane and ethylene (303 kJ/mol) as well as the direct cracking of propane to methane and ethylene (106.7 kJ/mol). The kinetic modeling revealed the positive effects of CO2 towards enhancing the propylene selectivity over the catalyst.