NOx storage capacity, SO2 resistance and regeneration of Pt/(Ba)/CeZr model catalysts for NOx-trap system
Résumé
NOx storage capacity, sulphur resistance and regeneration of 1wt%Pt/Ce 0.7Zr 0.3 O2 (Pt/CeZr) and 1wt%Pt/10wt%BaO/
Ce0.7Zr 0.3 O2 (Pt/Ba/CeZr) catalysts were studied and compared to a 1wt%Pt/10wt%BaO/Al2 O3 (Pt/Ba/Al) model catalyst
submitted to the same treatments. Pt/Ba/CeZr presents the best NOx storage capacity at 400 °C in accordance with basicity
measurements by CO2 TPD and Pt/CeZr shows the better performance at 200 °C mainly due to a low sensitivity to CO2 at this
temperature. For all samples, sulphating induces a detrimental effect on NOx storage capacity but regeneration at 550 °C under
rich conditions generally leads to the total recovery of catalytic performance. However, the nearly complete sulphur elimination is
only observed on Pt/CeZr. Moreover, an oxidizing treatment at 800 °C leads to partial sulphates elimination on the Pt/CeZr
catalyst whereas a stabilization of sulphates on Ba containing species is observed.