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SO2-induced stability of Ag-alumina catalysts in the SCR of NO with methane

Paper ID Volume ID Publish Year Pages File Format Full-Text
48126 46494 2009 8 PDF Available
Title
SO2-induced stability of Ag-alumina catalysts in the SCR of NO with methane
Abstract

We report on a stabilization effect on the structure and activity of Ag/Al2O3 for the selective catalytic reduction (SCR) of NOx with CH4 imparted by the presence of SO2 in the exhaust gas mixture. The reaction is carried out at temperature above 600 °C to keep the surface partially free of sulfates. In SO2-free gases, catalyst deactivation is fast and measurable at these temperatures. Time-resolved TEM analyses of used samples have determined that deactivation is due to sintering of silver from well-dispersed clusters to nanoparticles to micrometer-size particles with time-on-stream at 625 °C. However, sintering of silver was dramatically suppressed by the presence of SO2 in the reaction gas mixture. The structural stabilization by SO2 was accompanied by stable catalyst activity for the NO reduction to N2. The direct oxidation of methane was suppressed, thus the methane selectivity was improved in SO2-laden gas mixtures. In tests with high-content silver alumina with some of the silver present in metallic form, an increase in the SCR activity was found in SO2-containing gas mixtures. This is attributed to redispersion of the silver particles by SO2, an unexpected finding. The catalyst performance was reversible over many cycles of operation at 625 °C with the SO2 switched on and off in the gas mixture.

Keywords
Silver catalyst; Alumina; Sintering; Dispersion; SO2; SCR of NO; CH4; NOx reduction
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SO2-induced stability of Ag-alumina catalysts in the SCR of NO with methane
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 88, Issues 1–2, 29 April 2009, Pages 98–105
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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Any Questions? feel free to contact us