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Novel effect of SO2 on the SCR reaction over CeO2: Mechanism and significance

Paper ID Volume ID Publish Year Pages File Format Full-Text
46306 46437 2013 10 PDF Available
Title
Novel effect of SO2 on the SCR reaction over CeO2: Mechanism and significance
Abstract

Ceria (CeO2) showed a poor activity for the selective catalytic reduction (SCR) of NO with NH3, while CeO2 showed an excellent SCR activity in the presence of SO2 at 300–500 °C. The promotion of SO2 on the SCR reaction over CeO2 was mainly due to the sulfation of CeO2. The SCR reaction over CeO2 and that over sulfated CeO2 both followed the Eley–Rideal mechanism (i.e. the reaction between activated NH3 with gaseous NO). Meanwhile, the catalytic oxidization of NH3 to NO could simultaneously happen during the SCR reaction, resulting in a drop of NOx conversion at high temperatures. The adsorption of NH3 on CeO2 was obviously promoted after the sulfation, resulting in an obvious promotion of the Eley–Rideal mechanism. Meanwhile, the adsorption sites for NH2 adsorption and the oxidization agents for NH2 oxidization on CeO2 were separated after the sulfation. Thus, the probability of the collision between NH2 and Ce4+ on sulfated CeO2 was much less than that on CeO2, resulting in an obvious repression of the catalytic oxidization of NH3 to NO. As a result, the SCR activity of sulfated CeO2 was much better than that over CeO2.

Graphical abstract.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The promotion of SO2 on the SCR reaction was due to the sulfation of CeO2. ► The SCR reaction over CeO2 and sulfated CeO2 followed the E–R mechanism. ► The SCR reaction through the E–R mechanism was promoted after CeO2 sulfation. ► Catalytic oxidization of NH3 to NO over CeO2 was restrained after sulfation.

Keywords
SO2 effect; CeO2; Sulfation; NH3 adsorption; Eley–Rideal mechanism; Catalytic oxidization of NH3 to NO
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Novel effect of SO2 on the SCR reaction over CeO2: Mechanism and significance
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volumes 136–137, 5 June 2013, Pages 19–28
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Price was $35.95
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100% Money Back Guarantee
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