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Platinum oxide formation and reduction during NO oxidation on a diesel oxidation catalyst—Macrokinetic simulation

Paper ID Volume ID Publish Year Pages File Format Full-Text
46007 46428 2013 9 PDF Available
Title
Platinum oxide formation and reduction during NO oxidation on a diesel oxidation catalyst—Macrokinetic simulation
Abstract

The activity of a diesel oxidation catalyst (Pt-γ-Al2O3) is strongly influenced by the reaction conditions due to platinum oxidation, which drastically decreases the NO oxidation activity. Reactivation is possible with normal exhaust gas since platinum oxide can be reduced by NO in an atmosphere with high oxygen content at temperatures below 200 °C. A macrokinetic model is presented which takes into account the deactivation due to platinum oxidation. A standard model is extended by an additional balance of the platinum fraction and by reactions for platinum oxide formation (Pt + 0.5 O2 ⇌ PtO) and reduction (PtO + NO → Pt + 0.5 NO2). It is assumed (1) that platinum oxide is not inactive but has a lower activity, (2) that small amounts of NO2 have no impact on the oxidation in the presence of high oxygen concentrations and (3) that formation of PtO2 is negligible and that PtO is the main platinum oxide species formed. The NO oxidation rate is calculated for highly active sites (platinum) and sites with lower activity (platinum oxide). The actual reaction rate is calculated as a function of the platinum oxide fraction. With this extended macrokinetic model a good prediction of NO conversion is achieved. For model calibration and validation, isothermal experiments with either constant temperature or linear temperature ramps are employed. The model can be transferred to catalysts with lower platinum loading or aged catalysts, if only the NO oxidation on platinum and platinum oxide is reparameterised.

► Macro kinetic model taking into account PtO formation (Pt + 0.5O2 ↔ PtO) and reduction (PtO + NO ↔ Pt + 0.5NO2). ► NO oxidation rate depends on platinum oxide fraction. ► Model is validated by several experiments with either constant temperature or linear temperature ramp.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
NO oxidation; Platinum oxidation; Deactivation; Macrokinetic model; Inverse hysteresis
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Platinum oxide formation and reduction during NO oxidation on a diesel oxidation catalyst—Macrokinetic simulation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 129, 17 January 2013, Pages 273–281
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