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The effect of O2 on the NO–CO reaction over Ag–Pd/Al2O3: An in situ infrared study

Paper ID Volume ID Publish Year Pages File Format Full-Text
52773 46886 2009 6 PDF Available
Title
The effect of O2 on the NO–CO reaction over Ag–Pd/Al2O3: An in situ infrared study
Abstract

The effect of O2 on the NO–CO reaction over Pd/Al2O3 and Ag–Pd/Al2O3 has been studied by in situ infrared (IR) spectroscopy coupled with the O2 pulse technique at 373–573 K. Pulsing O2 into the NO–CO flow at 373 K causes the oxidation of Pd+–NO to gaseous NO2 over Pd/Al2O3 and the emergence of Pd0–NO on Ag–Pd/Al2O3. The formation of Pd0–NO during the O2 pulse over Ag–Pd/Al2O3 catalyst suggests that (i) O2 disrupts the Ag overlayers on the Pd surface, allowing the Pd surface to be exposed to NO; and (ii) Ag species is able to keep the Pd surface in reduced state in the presence of O2. Increasing the temperature to 573 K does not lead to the formation of Pd+–NO, over Ag–Pd/Al2O3 further supporting the unique ability of Ag to keep Pd in the reduced state under an oxidizing environment. Ag enhances NO oxidation and slow down CO oxidation on Pd/Al2O3. Adsorbed oxygen on Ag–Pd/Al2O3 exhibits two distinctly different reactivities: (i) a more active adsorbed oxygen reacting with NO, giving a sharp NO2 response and (ii) a less active species with, respect to NO, oxidizing CO, giving a trailing CO2 response. Ag is unable to alleviate the negative impact of O2 on the NO–CO reaction over Pd/Al2O3. Keeping Pd in the reduced state is not a necessary condition for nullifying the impact of O2 on the NO–CO reaction.

Keywords
NO–CO reaction; In situ IR; NOx reduction
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The effect of O2 on the NO–CO reaction over Ag–Pd/Al2O3: An in situ infrared study
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Communications - Volume 10, Issue 9, 25 April 2009, Pages 1313–1318
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