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Potential synergic effect between MOR and BEA zeolites in NOx SCR with methane: A dual bed design approach

Paper ID Volume ID Publish Year Pages File Format Full-Text
39064 45802 2015 8 PDF Available
Title
Potential synergic effect between MOR and BEA zeolites in NOx SCR with methane: A dual bed design approach
Abstract

•MOR and BEA zeolite catalysts containing Pd and Ce were prepared in a similar way.•Characterisation evidenced different metal species in each catalyst.•Catalyst exhibited different NO oxidation and NOx CH4–SCR performances.•Dual bed configuration revealed a potential synergic effect for NOx CH4–SCR.

The selective catalytic reduction of NOx with methane (NOx CH4–SCR) under lean conditions was investigated with catalysts based on two different zeolite structures (MOR and BEA) containing Pd and Ce. The catalytic performance for NO oxidation to NO2 reaction, considered an important first key step in the NOx CH4–SCR mechanism, was also assessed.Pd(0.3)Ce(2)–HBEA was found to be very active for NO oxidation but exhibits poor activity for NOx CH4–SCR. Conversely, Pd(0.3)Ce(2)–HMOR presents modest activity for NO oxidation, compared to Pd(0.3)Ce(2)–HBEA, but exhibits mild activity for NOx CH4–SCR reaction. Characterisation by H2–TPR, DRS UV–vis, TEM/EDS and FTIR-CO allowed the identification of palladium stabilised as Pd2+ ions in exchange positions in both monometallic and bimetallic MOR based catalysts, whereas, in BEA catalysts, it is presented as PdO clusters. Cerium is stabilised in Pd(0.3)Ce(2)–HMOR as small CeO2 particles, whereas, in Pd(0.3)Ce(2)–HBEA, it is present as large clusters. Catalysts were also tested in dual bed configuration, in which Pd(0.3)Ce(2)–HBEA was placed as first layer and Pd(0.3)Ce(2)–HMOR as second layer in the catalytic bed. The catalytic performance was significantly improved (higher NOx conversion into N2 and higher CH4 selectivity to SCR reaction), when compared to the catalytic performance of each catalyst individually, suggesting the existence of a synergic effect. This synergy is explained by the complementary roles that each catalyst play in HC–SCR mechanism.

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Keywords
NOx HC–SCR; Methane; MOR; BEA; Palladium; Cerium; Synergy
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Potential synergic effect between MOR and BEA zeolites in NOx SCR with methane: A dual bed design approach
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 506, 5 October 2015, Pages 246–253
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
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Any Questions? feel free to contact us