fulltext.study @t Gmail

Selective oxidation of ammonia to nitrogen on bi-functional Cu–SSZ-13 and Pt/Al2O3 monolith catalyst

Paper ID Volume ID Publish Year Pages File Format Full-Text
53279 46961 2016 15 PDF Available
Title
Selective oxidation of ammonia to nitrogen on bi-functional Cu–SSZ-13 and Pt/Al2O3 monolith catalyst
Abstract

•Addition of Cu–SSZ-13 layer gives trade-off between NH3 conversion and N2 selectivity.•With feed NO, NH3 and NOx conversion increases with increased Cu–SSZ-13 loading.•Dual-layer catalyst has lower NOx selectivity than mixed catalyst at high temperature.•Mixed-layer catalyst has higher NH3 conversion due to reduced mass transfer resistance.•Hybrid dual + mixed layer catalyst exploits beneficial features of both types.

The selective oxidation of NH3 to N2 on bi-functional mixed and dual-layer Cu–SSZ-13 and Pt/Al2O3 washcoated monolith catalysts is investigated under several reaction conditions to probe the effects of the added mass transfer barrier, in terms of the SCR loading (layer thickness), on the activity and selectivity of the catalyst. The combination of Cu–SSZ-13, itself shown to have high activity in reducing NOx to N2 with NH3, and Pt/Al2O3 is effective in converting the NOx produced by the very active but poorly selective precious metal catalyst. The data reveal a trade-off between NH3 conversion and N2 selectivity due to the mass transport barrier afforded by the added Cu–SSZ-13 top-layer: NH3 conversion decreases while N2 selectivity increases as Cu–SSZ-13 loading is increased. In the presence of feed NO, the NOx conversion of the dual-layer catalyst increases with an increase in the Cu–SSZ-13 washcoat loading. In the absence of feed NO, the dual-layer catalyst has a high selectivity to N2 due to the selective reaction in the Cu–SSZ-13 layer between NH3 from the bulk and counter-diffusing NOx formed in the underlying Pt/Al2O3. For the same catalyst loadings, the mixed washcoat catalyst gives a higher NH3 conversion at high space velocity than the dual-layer catalyst. This is attributed to NH3 conversion on Pt/Al2O3 sites not impeded by a SCR catalyst top-layer. In the presence of feed NO, the dual-layer catalyst shows a high NOx to N2 conversion as a result of the high SCR activity of the Cu–SSZ-13 top-layer. The mixed catalyst is more selective to NOx because the Pt catalyst in proximity to the SCR catalyst leads to the oxidation of NH3 back to NOx. Finally, we demonstrate that a hybrid catalyst having dual-layer and mixed catalyst attributes exhibits good performance by exploiting the beneficial effects of both catalyst types.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (133 K)Download as PowerPoint slide

Keywords
Ammonia slip catalyst; Ammonia oxidation; Platinum; Cu–SSZ-13; Selective catalytic reduction
First Page Preview
Selective oxidation of ammonia to nitrogen on bi-functional Cu–SSZ-13 and Pt/Al2O3 monolith catalyst
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
Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 267, 1 June 2016, Pages 130–144
Authors
, , , , , ,
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