Documents disponibles écrits par cet auteur

Adsorption and desorption of SOx on diesel oxidation catalysts / Oliver Krocher in Industrial & engineering chemistry research, Vol. 48 N° 22 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 22 (Novembre 2009) . - pp. 9847–9857 Titre : Adsorption and desorption of SOx on diesel oxidation catalysts Type de document : texte imprimé Auteurs : Oliver Krocher, Auteur ; Markus Widmer, Auteur ; Martin Elsener, Auteur Année de publication : 2010 Article en page(s) : pp. 9847–9857 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : NO  oxidation  SO2Diesel  oxidation  catalysts Résumé : The deactivation of NO oxidation by SO2 was studied with the use of commercial diesel oxidation catalysts (DOC) and Pt/Al2O3 as reference material, coated on cordierite monolith. Despite their slightly different elemental compositions, the NO conversion rates of the fresh commercial catalysts were very similar. The maximum NO conversion was 38% at 350 °C, and above this temperature conversion started to be limited by the thermodynamics of the reaction. The rates of NO conversion strongly decreased with the start of SO2 dosing. For analysis of SO2 conversion and uptake, SO2 and SO3/H2SO4 were determined separately in the gas phase by absorption and titration. Under typical exhaust gas conditions (1 ppm SO2, 250 °C), the catalysts functioned as sulfur traps and stored a large part of the emitted SO2. The SOx storage was divided into two phases: a fast saturation of the catalyst surface with sulfuric acid, which hampered NO conversion, and a slow, long-lasting sulfation of the washcoat. The storage capacities of the oxidation catalysts reached their maxima at 250 °C due to the temperature dependency of sulfur adsorption and desorption. Adsorbed sulfuric acid desorbed between 350 and 400 °C, whereas more stable compounds, such as aluminum sulfate, were decomposed at higher temperatures. Deactivated catalysts could be completely regenerated within a few minutes at temperatures above 350 °C. However, repeated or lengthier thermal treatments resulted in a reduced sulfur storage capacity and irreversible activity losses for NO oxidation due to a reduction of the active surface by sintering. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900882p [article] Adsorption and desorption of SOx on diesel oxidation catalysts [texte imprimé] / Oliver Krocher, Auteur ; Markus Widmer, Auteur ; Martin Elsener, Auteur . - 2010 . - pp. 9847–9857. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 22 (Novembre 2009) . - pp. 9847–9857 Mots-clés : NO  oxidation  SO2Diesel  oxidation  catalysts Résumé : The deactivation of NO oxidation by SO2 was studied with the use of commercial diesel oxidation catalysts (DOC) and Pt/Al2O3 as reference material, coated on cordierite monolith. Despite their slightly different elemental compositions, the NO conversion rates of the fresh commercial catalysts were very similar. The maximum NO conversion was 38% at 350 °C, and above this temperature conversion started to be limited by the thermodynamics of the reaction. The rates of NO conversion strongly decreased with the start of SO2 dosing. For analysis of SO2 conversion and uptake, SO2 and SO3/H2SO4 were determined separately in the gas phase by absorption and titration. Under typical exhaust gas conditions (1 ppm SO2, 250 °C), the catalysts functioned as sulfur traps and stored a large part of the emitted SO2. The SOx storage was divided into two phases: a fast saturation of the catalyst surface with sulfuric acid, which hampered NO conversion, and a slow, long-lasting sulfation of the washcoat. The storage capacities of the oxidation catalysts reached their maxima at 250 °C due to the temperature dependency of sulfur adsorption and desorption. Adsorbed sulfuric acid desorbed between 350 and 400 °C, whereas more stable compounds, such as aluminum sulfate, were decomposed at higher temperatures. Deactivated catalysts could be completely regenerated within a few minutes at temperatures above 350 °C. However, repeated or lengthier thermal treatments resulted in a reduced sulfur storage capacity and irreversible activity losses for NO oxidation due to a reduction of the active surface by sintering. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900882p