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In situ FTIR characterization of NH3 adsorption and reaction with O2 and CO on Pd-based FCC emission control additives

Paper ID Volume ID Publish Year Pages File Format Full-Text
41616 45895 2011 11 PDF Available
Title
In situ FTIR characterization of NH3 adsorption and reaction with O2 and CO on Pd-based FCC emission control additives
Abstract

The adsorption of NH3 and its reaction with O2 and CO over Cen+/Na+/γ-Al2O3 and Pd/Cen+/Na+/γ-Al2O3 was examined by FTIR spectroscopy in a wide range of temperatures. Ammonia undergoes decomposition on the surfaces of these materials at elevated temperatures with a fraction of the NH3 species being oxidized by lattice oxygen to NOx, which is trapped on the surface in the form of nitrites. The presence of O2 in the feed accelerates the formation of surface nitrite and nitrate species. The reaction of these species with ammonia at 400 °C is fast, producing N2. The presence of CO in the gaseous feed leads to the formation of surface isocyanates, presumably through the reaction with partially dehydrogenated surface NHx species. The PdO component mildly promotes the formation of these isocyanate species. Both the NCO and NO3−/NO2− species identified on the surfaces of these materials at elevated temperatures are active intermediates, participating in further reactions which ultimately lead to the reduction of NOx and CO emissions. The contribution of these intermediates to a possible N2 formation reaction network should be accounted for when FCC regenerators are operating under partial or incomplete burn combustion modes.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (195 K)Download as PowerPoint slideResearch highlights▶ NH3 can decompose on Cen+/Na+/γ-Al2O3 and react with surface oxygen. ▶ Products are trapped on the catalyst surface in the form of nitrates and nitrites. ▶ At 400 °C NH3 further reacts with surface nitrites/nitrates to form N2. ▶ NH3 and CO react over Pdn+/Cen+/Na+/γ-Al2O3 to form surface isocyanates.

Keywords
FTIR spectroscopy; FCC additives; NOx reduction; Palladium; Ammonia; Isocyanates; Nitrites; Nitrates
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In situ FTIR characterization of NH3 adsorption and reaction with O2 and CO on Pd-based FCC emission control additives
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 391, Issues 1–2, 4 January 2011, Pages 11–21
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