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Evaluation of H2 effect on NO oxidation over a diesel oxidation catalyst

Paper ID Volume ID Publish Year Pages File Format Full-Text
45484 46412 2015 9 PDF Available
Title
Evaluation of H2 effect on NO oxidation over a diesel oxidation catalyst
Abstract

•Effect of H2 on NO oxidation is investigated in varied mixtures of DOC feed•Chemical and exothermal effect due to H2 addition were discriminated•H2 prevents low temperature Pt oxide formation•Addition of H2 weakens C3H6 inhibition effect on NO oxidation•Promotional chemical effect of H2 is to prevent C3H6 oxidation with NO2

The influence of H2 on NO oxidation over Pt/Al2O3 as a model DOC catalyst was evaluated with various DOC feed mixtures. Discrimination of surface chemistry and exothermal effects due to addition of H2 was made based on differences in time scales of transient responses. H2 was proposed to retard Pt oxide formation mainly at low temperatures (ca. <200 °C), whereas, at higher temperatures Pt oxide formation was unhindered by H2. As a result, a temporal enhancement in NO2 yield due to H2 was obtained during temperature ramp experiments. In C3H6 containing mixtures, it was evident that the promotional role of H2 was to weaken the inhibition effect of C3H6 by lowering the light-off temperature for C3H6 oxidation. The results from transient experiments clearly showed an increase in NO2 yield that resulted from effects of H2 on surface chemistry and/or reactions. H2 decreased the blocking effect of adsorbed C3H6 species and prevented the reaction of C3H6 with NO2 forming NO. For a complete DOC feed mixture (containing NO, CO, C3H6), an addition of ca. 250 ppm of H2 appeared to be optimal, while higher H2 concentrations were disadvantageous due to NO2 consumption by H2.

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Keywords
Hydrogen; Diesel oxidation catalyst; NO oxidation; Pt oxide; Exhaust emission
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 179, December 2015, Pages 542–550
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