NOx storage and reduction properties of Pt/CexZr1−xO2 mixed oxides: Sulfur resistance and regeneration, and ammonia formation - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Applied Catalysis B: Environmental Année : 2009

NOx storage and reduction properties of Pt/CexZr1−xO2 mixed oxides: Sulfur resistance and regeneration, and ammonia formation

Résumé

The influence of the ceria-zirconia mixed oxide composition in Pt/CexZr1−xO2 catalysts was studied toward NOx storage capacity (NSC), including sulfur poisoning and sulfur regeneration, and NOx reduction efficiency in lean–rich cycling conditions. The results are compared with a Pt/Ba/Al model catalyst. The samples were characterized by N2 adsorption, XRD and H2-TPR. The behaviors of the ceria-zirconia supported catalysts are quite similar whatever their composition. They are sensitive to a reducing pretreatment which leads to an increase of (i) the cerium reducibility/oxygen mobility, (ii) the NO oxidation rate and (iii) the NOx storage capacity at 300 and 400 °C. The sulfating treatment leads to a dramatic decrease of the NOx storage capacity for all catalysts, the decrease being more pronounced for the Zr-rich samples. H2-TPR experiments show that the sulfates amount and their stability tend to increase with the Zr content, but these sulfates are significantly less stable compared with Pt/Ba/Al. The sulfur elimination rates in rich mixture at 550 °C are higher than 90% with the ceria-zirconia supported catalysts versus 56% with Pt/Ba/Al. The ceria-zirconia supported catalysts are able to convert NOx in lean–rich cycling condition. Compared with Pt/Ba/Al, the NOx conversions are a little lowered but the ammonia selectivity is significantly decreased with the Ce–Zr mixed oxides, with a beneficial influence of the cerium content.

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Catalyse
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hal-03108338 , version 1 (13-01-2021)

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N. Le Phuc, E.C. Corbos, Xavier Courtois, F. Can, P. Marecot, et al.. NOx storage and reduction properties of Pt/CexZr1−xO2 mixed oxides: Sulfur resistance and regeneration, and ammonia formation. Applied Catalysis B: Environmental, 2009, 93 (1-2), pp.12-21. ⟨10.1016/j.apcatb.2009.09.007⟩. ⟨hal-03108338⟩

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