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Ammonia formation over supported platinum and palladium catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
45528 46416 2015 10 PDF Available
Title
Ammonia formation over supported platinum and palladium catalysts
Abstract

•Effect of oxygen on ammonia formation from NO + H2 and NO + CO + H2O gas mixtures for passive SCR applications.•Promoting effect of oxygen on ammonia formation over titania supported noble metal catalysts.•WGS reaction and formation/hydrolysis of surface isocyanate species are important routes in the formation of ammonia from NO + CO + H2O gas mixtures.

We report experimental results for the formation of ammonia from nitric oxide and hydrogen, and from nitric oxide, water and carbon monoxide over silica, alumina and titania supported platinum and palladium catalysts. Temperature programmed reaction experiments in gas flow reactor show a considerable formation of ammonia in the temperature range 200–450 °C, which is suppressed by the presence of excess oxygen. However, oxygen sweep experiments show that for the titania supported catalysts minor amounts of oxygen promotes the ammonia formation at low temperatures. In situ DRIFT spectroscopy measurements indicate that cyanate species on the support play an important role in the ammonia formation mechanism. This work shows that alumina supported palladium is a promising system for passive selective catalytic reduction applications, exhibiting low-temperature activity during the water–gas-shift assisted ammonia formation reaction. Conversely, titania supported samples are less active for ammonia formation as a result of the poor thermal stability of the titania support.

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Keywords
Catalytic exhaust aftertreatment; Passive-SCR; NOxreduction; In situ DRIFT spectroscopy; NH3 formation
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Ammonia formation over supported platinum and palladium catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 165, April 2015, Pages 10–19
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