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NOx storage/reduction over lean-burn automotive catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
48801 46522 2007 7 PDF Available
Title
NOx storage/reduction over lean-burn automotive catalysts
Abstract

This paper shows the behavior of a Pt/Ba/γ–Al2O3 automotive catalyst in a fixed bed reactor during cyclic operation at lean and rich gas phase conditions at short (seconds) and long (hours) cycling times at different temperatures. Reactor exit gas phase concentrations have been measured and catalyst properties have been determined before and after selective cycling experiments. The experimental results indicate that: (i) Upon 9 h lean and 15 h rich cycling, the NO oxidation efficiency of the catalyst decreases with time while incomplete regeneration is seen, even after 15 h rich exposure with H2. The cyclic steady state is reached after 3 lean/rich cycles, at which only 60% of the available barium is involved in the NOx storage/reduction. (ii) The BET surface area, pore volume, and Pt dispersion decrease by approximately 40%, which may be a result of masking of Pt sites or blocking of pores of the barium clusters as BaCO3 becomes Ba(NO3)2. Experiments with catalyst pellet sizes of 180 and 280 μm along with XPS measurements show that blocking of catalyst pellet pores is not taking place. (iii) When applying lean/rich cycling in the order of seconds, it appears that catalyst history and lean/rich timing affect the number of cycles required to arrive at a closed N balance. XRD results after lean exposure confirm the formation of barium nitrate in the bulk of the barium cluster.

Keywords
NOx trap; Barium nitrate; Lean-burn; NOx storage; NOx reduction; Hydrogen
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NOx storage/reduction over lean-burn automotive catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 70, Issues 1–4, 31 January 2007, Pages 226–232
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