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Local ammonia storage and ammonia inhibition in a monolithic copper-beta zeolite SCR catalyst ⋆

Paper ID Volume ID Publish Year Pages File Format Full-Text
46538 46441 2012 9 PDF Available
Title
Local ammonia storage and ammonia inhibition in a monolithic copper-beta zeolite SCR catalyst ⋆
Abstract

Selective catalytic reduction of NO with NH3 was studied on a Cu-beta zeolite catalyst, with specific focus on the distributed NH3 capacity utilization and inhibition. In addition, several other relevant catalyst parameter distributions were quantified including the SCR zone, or catalyst region where SCR occurs, and NO and NH3 oxidation. We show that the full NH3 capacity (100% coverage) is used within the SCR zone for a range of temperatures. By corollary, unused NH3 capacity exists downstream of the SCR zone. Consequently, the unused capacity relative to the total capacity is indicative of the portion of the catalyst unused for SCR. Dynamic NH3 inhibition distributions, which create local transient conversion inflections, are measured. Dynamic inhibition is observed where the gas phase NH3 and NO concentrations are high, driving rapid NH3 coverage buildup and SCR. Accordingly, we observe dynamic inhibition at low temperatures and in hydrothermally aged states, but predict its existence very near the catalyst front in higher conversion conditions where we did not specifically monitor its impact. While this paper addresses some general distributed SCR performance parameters including Oxidation and SCR zone, our major new contributions are associated with the NH3 capacity saturation within the SCR zone and dynamic inhibition distributions and the associated observations. These new insights are relevant to developing accurate models, designs and control strategies for automotive SCR catalyst applications.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights▸ We characterize the transient distributed performance of a Cu-beta SCR catalyst. ▸ The intra-SCR zone can vary dramatically with constant integral performance. ▸ The NH3 capacity is practically saturated over the SCR zone. ▸ Fast NH3 coverage buildup drives dynamic inhibition conversion inflections. ▸ Inhibited conditions can be accessed without experiencing dynamic inhibition.

Keywords
SCR; Ammonia; NO; NH3 capacity; NH3 inhibition; Distributed reactions; Cu-beta; Zeolite
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Local ammonia storage and ammonia inhibition in a monolithic copper-beta zeolite SCR catalyst ⋆
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 126, 25 September 2012, Pages 144–152
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