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A comparative kinetics study between Cu/SSZ-13 and Fe/SSZ-13 SCR catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
53609 46977 2015 12 PDF Available
Title
A comparative kinetics study between Cu/SSZ-13 and Fe/SSZ-13 SCR catalysts
Abstract

•Cu/SSZ-13 gains oxidation activity after aging while the opposite is found for Fe/SSZ-13.•Mixed Cu/SSZ-13 and Fe/SSZ-13 provide more stable performance in SCR.•Hysteresis in standard and fast SCR can be rationalized from NH3 and NH4NO3 inhibition, respectively.

Cu- and Fe/SSZ-13 catalysts with the same Cu(Fe)/Al ratios are synthesized using the same parent SSZ-13 starting material. The catalytic performance for both fresh and hydrothermally aged catalysts is tested with NO and NH3 oxidation, and standard SCR reactions under steady-state conditions, and standard and fast SCR under temperature-programmed conditions. For standard SCR, Cu/SSZ-13 shows much better low-temperature performance which can be explained by NH3-inhibition of Fe/SSZ-13. During hydrothermal aging, both catalysts undergo dealumination but Fe/SSZ-13 dealuminates more severely. For aged catalysts, Cu/SSZ-13 gains oxidation activities due to formation of CuOx. However, Fe/SSZ-13 loses oxidation activities although formation of FeOx clusters and FeAlOx species also occur. Because of such physical properties differences, aged Cu/SSZ-13 loses while Fe/SSZ-13 maintains high-temperature SCR selectivities. A physical mixture of aged catalysts provides stable SCR performance in a wide temperature range and is able to decrease N2O formation at high reaction temperatures. This suggests that Fe/SSZ-13 can be used as a cocatalyst for Cu/SSZ-13 for transportation applications. During temperature-programmed SCR reactions, weak hysteresis is found during standard SCR due to NH3 inhibition. For fast SCR, hysteresis caused by NH4NO3 inhibition is much more significant. NH4NO3 deposition is greatly enhanced by Brønsted and Lewis acidity of the catalysts.

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Keywords
Selective catalytic reduction; Chabazite; SSZ-13; Diesel engine; Emission control
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A comparative kinetics study between Cu/SSZ-13 and Fe/SSZ-13 SCR catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 258, Part 2, 1 December 2015, Pages 347–358
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
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Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us