| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 6467639 | Chemical Engineering Science | 2017 | 14 Pages |
•A micro-kinetic model for CO/C3H6/C2H6/H2 oxidation on Pt/Al2O3 is developed.•Inverse hysteresis is mainly due to formation of surface intermediates.•The possibility of steam reforming of C2H6 happening before oxidation is illustrated.•Hysteresis predicted by global and micro-kinetic models differs substantially.
An elementary step mechanism, which accounts for adsorption, desorption and surface reaction steps is proposed for co-oxidation of CO, propylene, hydrogen and ethane on Pt/Al2O3. Parameter estimation is used to determine the kinetic parameters for these steps, which depend on platinum loading and dispersion. A micro-kinetic model is proposed for water-gas shift reaction that captures the experimental trend observed during co-oxidation of CO/H2. This mechanism is used to predict hysteresis features during oxidation and co-oxidation reactions. The oxidation of all the individual reactants exhibits regular hysteresis and the model predicts the experimentally observed inverse hysteresis during co-oxidation of CO and C3H6. The inverse hysteresis is caused by surface intermediates formed during C3H6 oxidation. These surface intermediates block the active sites, decreasing the light-off activity of CO during ramp down. The developed micro-kinetic model can also explain steam reforming of propylene and ethane on Pt/Al2O3. Finally, we compare the predicted hysteresis during CO oxidation by global and micro-kinetic models. The predicted ignition temperature by both global and micro-kinetic models is almost same. However, the predicted extinction temperature by the global and micro-kinetic models is rather different. This behavior is due to different rate determining step during ramp down period.
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