Role of the Nature of the Support (Alumina or Silica), of the Support Porosity, and of the Pt Dispersion in the Selective Reduction of NO by C3H6 under Lean-Burn Conditions

During selective reduction of NOx under lean-burn conditions, a Pt particle size dependency has previously been observed with various supports. In this study, we have examined the influence of various parameters over a large range of initial metal dispersion: nature of the support (silica or alumina...

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Published inJournal of catalysis Vol. 189; no. 2; pp. 410 - 420
Main Authors Denton, Patricia, Giroir-Fendler, Anne, Praliaud, Hélène, Primet, Michel
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier Inc 25.01.2000
Elsevier
Subjects
Catalysis
Catalysts: preparations and properties
Chemistry
DeNOx
dispersion
Exact sciences and technology
General and physical chemistry
Pt-supported catalysts
SCR NO
selective nitric oxide reduction
support effects
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
DeNOx
selective nitric oxide reduction
dispersion
Pt-supported catalysts
support effects
SCR NO
Nitrogen oxide
Hydrocarbon
Transition metal
Silica
Supported catalyst
Chemical reduction
Heterogeneous catalysis
Propene
Transmission electron microscopy
Platinum
Nitric oxide
Alumina
Catalyst support
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Summary:During selective reduction of NOx under lean-burn conditions, a Pt particle size dependency has previously been observed with various supports. In this study, we have examined the influence of various parameters over a large range of initial metal dispersion: nature of the support (silica or alumina), support porosity, presence of impurities (particularly chlorine or sulfur), nature of the platinum precursor salt, and Pt particle size distribution. Furthermore, we have considered the mean particle size after sintering under the reactant mixture up to 773 K. Of the factors considered, only the Pt dispersion is of key importance. The intrinsic activity increases with decreasing dispersion (measured initially or after reaction) for each of the main reactions: reduction of NO into N2 or N2O, oxidation of NO into NO2, or oxidation of C3H6 into CO2. The dispersion does not clearly affect the selectivity.
ISSN:0021-9517
1090-2694
DOI:10.1006/jcat.1999.2708