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

Paper ID Volume ID Publish Year Pages File Format Full-Text
47342 46469 2009 10 PDF Available
Title
NOx storage and reduction properties of Pt/CexZr1−xO2 mixed oxides: Sulfur resistance and regeneration, and ammonia formation
Abstract

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.

Keywords
NOx; Storage; Reduction; Ceria; Zirconia; Ammonia formation
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NOx storage and reduction properties of Pt/CexZr1−xO2 mixed oxides: Sulfur resistance and regeneration, and ammonia formation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 93, Issues 1–2, 25 November 2009, Pages 12–21
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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Any Questions? feel free to contact us