Catalytic combustion of soot was performed over ZnO:CeO2 catalysts obtained via a non‑alkoxide sol-gel route. Different kinetics parameters were calculated through thermal analyses, thus, enabling the correlation between the experimental data and the decomposition mechanisms probably associated with the soot decomposition in each case.
Keywords:
soot oxidation; mixed oxides; ceria; automotive catalysis; kinetics parameters
) and reused (magenta unfilled triangles; 
); CeO
); and fresh (magenta triangles, 
) ZnO:CeO
) for the catalytic ability of the prepared compounds on Printex-U
); ΔS
| Catalyst | Tia a Ti: soot oxidation ignition temperature; / °C | Tcb b Tc: temperature of the highest rate of soot combustion; / °C | Tfc c Tf : end of weight loss; / °C |
|---|---|---|---|
| Noned d None: corresponding to Printex-U® oxidation without a catalyst. | 450 | 610 | 660 |
| ZnO | 450 | 575 | 630 |
| CeO2 | 270 | 451 | 510 |
| ZnO:CeO2-fresh | 340 | 420 | 480 |
| ZnO:CeO2-used | 345 | 436 | 493 |
| Integral reaction model function | Printex-U® | CeO2/ Printex-U® | ZnO/ Printex-U® | ZnO:CeO2/ Printex-U®(fresh) | ZnO:CeO2/ Printex-U®(reused) |
|---|---|---|---|---|---|
| g1(α) = α 2 | 0.99297 | 0.98524 | 0.95031 | 0.96836 | 0.93527 |
| g2(α) = α (1– α) ln(1– α) | 0.99657 | 0.99324 | 0.96928 | 0.98289 | 0.95417 |
| g3(α) = [1 – (1–α)1/3]2 | 0.99758 | 0.99629 | 0.99398 | 0.99568 | 0.97891 |
| g4(α) = (1– 2/3 α) – (1– α)2/3 | 0.99534 | 0.99594 | 0.97909 | 0.98885 | 0.96359 |
| g5(α) = – ln(1– α) | 0.97088 | 0.98204 | 0.99684 | 0.99578 | 0.99270 |
| g6(α) = [– ln(1– α)]1/2 | 0.97088 | 0.98204 | 0.99684 | 0.99578 | 0.99270 |
| g7(α) = [– ln(1– α)]1/3 | 0.97088 | 0.98204 | 0.99684 | 0.99578 | 0.99270 |
| g8(α) = 1 – (1– α)1/2 | 0.99770 | 0.99678 | 0.98463 | 0.99170 | 0.96884 |
| g9(α) = 1 – (1– α)1/3 | 0.99758 | 0.99629 | 0.99398 | 0.99568 | 0.97891 |
| A / s-1 | Ea / (kJ mol-1) | ΔH / (kJ mol-1) | ΔS / (J mol-1K-1) | ΔG / (kJ mol-1) | |
|---|---|---|---|---|---|
| Printex-U® | 7.5 × 1012 | 175 | 181 | 7.4 | 174 |
| CeO2/Printex-U® | 6.3 × 107 | 79 | 73 | –102 | 147 |
| ZnO/Printex-U® | 9.8 × 108 | 104 | 98 | –81 | 166 |
| ZnO:CeO2/Printex-U® (fresh) | 1.9 × 106 | 54 | 49 | –131 | 141 |
| ZnO:CeO2/Printex-U® (reused) | 3.4 × 108 | 81 | 75 | –88 | 138 |
