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New insight into the interaction of sulfur with diesel NOx storage catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
48797 46522 2007 9 PDF Available
Title
New insight into the interaction of sulfur with diesel NOx storage catalysts
Abstract

A commercial NOx-storage catalyst (NSC) has been subjected to different aging procedures on the engine bench simulating 100,000 km mileage. The aging consisted of cyclical sulfur exposure, subsequent sulfur removal and testing of the catalytic activity. More aggressive desulfation procedures result in more efficient sulfur removal and consequently good high temperature NOx-conversion. However, low temperature NOx-performance is lower than for agings employing more moderate desulfation conditions.Sulfur post mortem analyses reveal a slight decrease of residual sulfur concentration over the length of all catalysts after completion of the aging. BET and CO-chemisorption data are in line with the increase of temperature from catalyst inlet to outlet during the desulfation. The conversion of BaCO3 to BaSO4 during the sulfur poisoning was followed by IR, TPD and TPR. A quantitative analysis of the data shows that at the end of the agings all residual sulfur is mainly located at barium sites as opposed to other oxide components like e.g. alumina or ceria. TPR data suggest that prolonged rich purges of the sulfated catalyst lead to an efficient decomposition of sulfates however some sulfur is being trapped in the form of BaS which seems difficult to remove under constant rich conditions.XPS data suggest that the bulk sulfur amounts in the catalyst may be decoupled from the actual concentration at the catalyst surface. In that sense, the residual sulfur concentration might be limited in some cases as a criterion to assess the performance of a NSC. More reducing desulfation conditions cause the residual sulfur to be present in the form of more reduced sulfur species (sulfites, sulfides) on the catalyst.

Keywords
NOx storage; Sulfur; Sulfur poisoning
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New insight into the interaction of sulfur with diesel NOx storage catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 70, Issues 1–4, 31 January 2007, Pages 189–197
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
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
Online Support
Any Questions? feel free to contact us