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Catalytic performance of rhodium-based catalysts for CO preferential oxidation in H2-rich gases / Camilla Karnfelt in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5304–5312 Titre : Catalytic performance of rhodium-based catalysts for CO preferential oxidation in H2-rich gases Type de document : texte imprimé Auteurs : Camilla Karnfelt, Auteur ; Stefania Specchia, Auteur ; Guido Saracco, Auteur Année de publication : 2008 Article en page(s) : p. 5304–5312 Note générale : Bibliogr. p. 5311-5312 Langues : Anglais (eng) Mots-clés : Rhodium-based  catalysts;  CO  preferential  oxidation;  Gas Résumé : CO preferential oxidation (CO-PROX) can lead to a reduction of the CO content in the hydrogen-rich gas derived from hydrocarbon re-forming down to at least 10 ppmv or below, so as to enable its direct feed to standard polymer electrolyte membrane fuel cells (PEM FCs). Rh-based catalysts supported on A zeolites (3A, 4A, and 5A), alumina, titania, and ceria were prepared and tested for potential application in CO-PROX operating over a temperature range compatible with PEM FCs (80−100 °C). Among the prepared catalysts, the 1% Rh-zeolite 3A catalyst, tested with a weight space velocity (WSV) of 0.66 N·L·min−1·gcat.−1, was found to be the most suitable one for the CO-PROX at low temperature: it reduced the inlet CO concentration below 10 ppmv within a temperature range of at least 80−120 °C without the appearance of undesirable side reactions. Tests at progressively lower O-to-CO feed ratio and the same WSV value were carried out for the sake of reducing H2 consumption and improving CO-PROX selectivity. For 1% Rh-3A zeolite the minimum λ value, ensuring a sufficiently wide temperature range of a nearly complete CO conversion at temperatures compatible with PEM FCs operation, was found to be equal to 3. Finally, to decrease the catalyst cost, the Rh load on the catalyst was tentatively reduced from 1 to 0.5%. A better distribution of the active element crystallites over the support surface was even obtained for this last catalyst. When operating at λ = 3 and at WSV = 0.66 N·L·min−1·gcat.−1, the 0.5% Rh-3A catalyst could effectively reduce the inlet CO concentration below 10 ppmv within a temperature range of 100−140 °C, without the appearance of undesired side reactions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0713588 [article] Catalytic performance of rhodium-based catalysts for CO preferential oxidation in H2-rich gases [texte imprimé] / Camilla Karnfelt, Auteur ; Stefania Specchia, Auteur ; Guido Saracco, Auteur . - 2008 . - p. 5304–5312. Bibliogr. p. 5311-5312 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5304–5312 Mots-clés : Rhodium-based  catalysts;  CO  preferential  oxidation;  Gas Résumé : CO preferential oxidation (CO-PROX) can lead to a reduction of the CO content in the hydrogen-rich gas derived from hydrocarbon re-forming down to at least 10 ppmv or below, so as to enable its direct feed to standard polymer electrolyte membrane fuel cells (PEM FCs). Rh-based catalysts supported on A zeolites (3A, 4A, and 5A), alumina, titania, and ceria were prepared and tested for potential application in CO-PROX operating over a temperature range compatible with PEM FCs (80−100 °C). Among the prepared catalysts, the 1% Rh-zeolite 3A catalyst, tested with a weight space velocity (WSV) of 0.66 N·L·min−1·gcat.−1, was found to be the most suitable one for the CO-PROX at low temperature: it reduced the inlet CO concentration below 10 ppmv within a temperature range of at least 80−120 °C without the appearance of undesirable side reactions. Tests at progressively lower O-to-CO feed ratio and the same WSV value were carried out for the sake of reducing H2 consumption and improving CO-PROX selectivity. For 1% Rh-3A zeolite the minimum λ value, ensuring a sufficiently wide temperature range of a nearly complete CO conversion at temperatures compatible with PEM FCs operation, was found to be equal to 3. Finally, to decrease the catalyst cost, the Rh load on the catalyst was tentatively reduced from 1 to 0.5%. A better distribution of the active element crystallites over the support surface was even obtained for this last catalyst. When operating at λ = 3 and at WSV = 0.66 N·L·min−1·gcat.−1, the 0.5% Rh-3A catalyst could effectively reduce the inlet CO concentration below 10 ppmv within a temperature range of 100−140 °C, without the appearance of undesired side reactions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0713588

NOx abatement by HC - assisted SCR over combustion synthesized - supported Ag catalysts / Murid Hussain in Industrial & engineering chemistry research, Vol. 51 N° 22 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7467-7474 Titre : NOx abatement by HC - assisted SCR over combustion synthesized - supported Ag catalysts Type de document : texte imprimé Auteurs : Murid Hussain, Auteur ; Nunzio Russo, Auteur ; Guido Saracco, Auteur Année de publication : 2012 Article en page(s) : pp. 7467-7474 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalyst  Combustion  Selective  catalytic  reduction  Pollution  abatement Résumé : In this work, catalysts containing 2% by weight of silver particles dispersed on different oxide supports (CeO2, La2O3, ZrO2,Al2O3), and oxides without silver particles were prepared by means of the combustion synthesis method. This cheap and quick technique has been developed to produce very fine, homogeneous, crystalline powders without the intermediate decomposition and/or calcining steps which other conventional synthesis routes require. These features are also interesting for the cosynthesis of supported Ag catalysts; it has in fact been possible in one-shot to achieve values of the Ag clusters (estimated size 5―10 nm) that are comparable with those obtained by means of the more complex methods reported in literature. The catalysts were characterized via XRD, BET, TEM, FESEM-EDS, and XPS analysis. The catalytic performances of the prepared catalysts were evaluated in a TPR apparatus for the selective reduction of NO with benzene in the presence of oxygen. A noticeable enhancement in activity was achieved when the selected oxides were doped with Ag. Lantana and ceria-supported Ag catalysts with good hydrothermal stability were found to perform comparatively well, as a significant NOx to N2 conversion was obtained at temperatures slightly above 250 °C. As far as the results concerning the catalysts are concerned, a synergic effect of the supports with the Ag clusters has been highlighted. Some conclusions may be drawn concerning the reaction mechanism. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968298 [article] NOx abatement by HC - assisted SCR over combustion synthesized - supported Ag catalysts [texte imprimé] / Murid Hussain, Auteur ; Nunzio Russo, Auteur ; Guido Saracco, Auteur . - 2012 . - pp. 7467-7474. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7467-7474 Mots-clés : Catalyst  Combustion  Selective  catalytic  reduction  Pollution  abatement Résumé : In this work, catalysts containing 2% by weight of silver particles dispersed on different oxide supports (CeO2, La2O3, ZrO2,Al2O3), and oxides without silver particles were prepared by means of the combustion synthesis method. This cheap and quick technique has been developed to produce very fine, homogeneous, crystalline powders without the intermediate decomposition and/or calcining steps which other conventional synthesis routes require. These features are also interesting for the cosynthesis of supported Ag catalysts; it has in fact been possible in one-shot to achieve values of the Ag clusters (estimated size 5―10 nm) that are comparable with those obtained by means of the more complex methods reported in literature. The catalysts were characterized via XRD, BET, TEM, FESEM-EDS, and XPS analysis. The catalytic performances of the prepared catalysts were evaluated in a TPR apparatus for the selective reduction of NO with benzene in the presence of oxygen. A noticeable enhancement in activity was achieved when the selected oxides were doped with Ag. Lantana and ceria-supported Ag catalysts with good hydrothermal stability were found to perform comparatively well, as a significant NOx to N2 conversion was obtained at temperatures slightly above 250 °C. As far as the results concerning the catalysts are concerned, a synergic effect of the supports with the Ag clusters has been highlighted. Some conclusions may be drawn concerning the reaction mechanism. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968298