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Iron-ceria aerogels doped with palladium as water−gas shift catalysts for the production of hydrogen / Bali, Sumit in Industrial & engineering chemistry research, Vol. 49 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1652–1657 Titre : Iron-ceria aerogels doped with palladium as water−gas shift catalysts for the production of hydrogen Type de document : texte imprimé Auteurs : Bali, Sumit, Auteur ; Huggins, Frank E., Auteur ; Ernst, Richard D., Auteur Année de publication : 2010 Article en page(s) : pp 1652–1657 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Iron  oxide  Cerium  oxide  catalys. Résumé : Mixed 4.5% iron oxide−95.5% cerium oxide aerogels doped with 1% and 2% palladium (Pd) by weight have been synthesized, and their activities for the catalysis of water−gas shift (WGS) reaction have been determined. The aerogels were synthesized using propylene oxide as the proton scavenger for the initiation of hydrolysis and polycondensation of a homogeneous alcoholic solution of cerium(III) chloride heptahydrate and iron(III) chloride hexahydrate precursor. Palladium was doped onto some of these materials by gas-phase incorporation (GPI) using (η3-allyl)(η5-cyclopentadienyl)palladium as the volatile Pd precursor. Water−gas shift catalytic activities were evaluated in a six-channel fixed-bed reactor at atmospheric pressure and reaction temperatures ranging from 150 to 350 °C. Both 1% and 2% Pd-doped 4.5% iron oxide−95.5% cerium oxide aerogels showed WGS activities that increased significantly from 150 to 350 °C. The activities of 1% Pd-doped 4.5% iron oxide−95.5% cerium oxide aerogels were also compared with that of the 1% Pd-doped ceria aerogel without iron. The WGS activity of 1% Pd on 4.5% iron oxide−95.5% cerium oxide aerogels is substantially higher (5 times) than the activity of 1% Pd-doped ceria aerogel without iron. The gas-phase incorporation results in a better Pd dispersion. Ceria aerogel provides a nonrigid structure wherein iron is not significantly incorporated inside the matrix, thereby resulting in better contact between the Fe and Pd and thus enhancing the WGS activity. Further, neither Fe nor Pd is reduced during the ceria-aerogel-catalyzed WGS reaction. This behavior contrasts with that noted for other Fe-based WGS catalysts, in which the original ferric oxide is typically reduced to a nonstoichiometric magnetite form. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901543w [article] Iron-ceria aerogels doped with palladium as water−gas shift catalysts for the production of hydrogen [texte imprimé] / Bali, Sumit, Auteur ; Huggins, Frank E., Auteur ; Ernst, Richard D., Auteur . - 2010 . - pp 1652–1657. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1652–1657 Mots-clés : Iron  oxide  Cerium  oxide  catalys. Résumé : Mixed 4.5% iron oxide−95.5% cerium oxide aerogels doped with 1% and 2% palladium (Pd) by weight have been synthesized, and their activities for the catalysis of water−gas shift (WGS) reaction have been determined. The aerogels were synthesized using propylene oxide as the proton scavenger for the initiation of hydrolysis and polycondensation of a homogeneous alcoholic solution of cerium(III) chloride heptahydrate and iron(III) chloride hexahydrate precursor. Palladium was doped onto some of these materials by gas-phase incorporation (GPI) using (η3-allyl)(η5-cyclopentadienyl)palladium as the volatile Pd precursor. Water−gas shift catalytic activities were evaluated in a six-channel fixed-bed reactor at atmospheric pressure and reaction temperatures ranging from 150 to 350 °C. Both 1% and 2% Pd-doped 4.5% iron oxide−95.5% cerium oxide aerogels showed WGS activities that increased significantly from 150 to 350 °C. The activities of 1% Pd-doped 4.5% iron oxide−95.5% cerium oxide aerogels were also compared with that of the 1% Pd-doped ceria aerogel without iron. The WGS activity of 1% Pd on 4.5% iron oxide−95.5% cerium oxide aerogels is substantially higher (5 times) than the activity of 1% Pd-doped ceria aerogel without iron. The gas-phase incorporation results in a better Pd dispersion. Ceria aerogel provides a nonrigid structure wherein iron is not significantly incorporated inside the matrix, thereby resulting in better contact between the Fe and Pd and thus enhancing the WGS activity. Further, neither Fe nor Pd is reduced during the ceria-aerogel-catalyzed WGS reaction. This behavior contrasts with that noted for other Fe-based WGS catalysts, in which the original ferric oxide is typically reduced to a nonstoichiometric magnetite form. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901543w

Synthetic doped amorphous ferrihydrite for the fischer – tropsch synthesis of alternative fuels / Bali, Sumit in Industrial & engineering chemistry research, Vol. 51 N° 12 (Mars 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4515–4522 Titre : Synthetic doped amorphous ferrihydrite for the fischer – tropsch synthesis of alternative fuels Type de document : texte imprimé Auteurs : Bali, Sumit, Auteur ; Garima Bali, Auteur ; Frank E. Huggins, Auteur Année de publication : 2012 Article en page(s) : pp. 4515–4522 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Ferrihydrites  Oxyhydroxide  minerals Résumé : Ferrihydrites (FHYDs) with the general formula of FeOOH·nH2O are naturally occurring oxyhydroxide minerals found in environments varying from river beds, lakes, and marshes to even living organisms. Here, we report the synthesis of a new kind of synthetic doped amorphous two-line FHYDs containing aluminum and copper, which are not usually known to be found in nature. Transmission electron microscopy carried out on synthetic FHYDs showed them to be amorphous in nature with some nanosized groupings in the form of nanoclusters of about 50–200 nm size without any hint of diffraction fringes associated with crystalline order. The synthetic doped FHYDs exhibit unique properties and have been characterized extensively by magnetic measurements, X-ray diffraction, and electron microscopy as well as by Mössbauer spectroscopic studies. After promotion with potassium, these FHYDs were found to have high activity as catalysts for the Fischer–Tropsch (F–T) conversion of syngas to liquid fuels over a period of 100 h in a fixed bed reactor at 265 °C and 100 psig pressures. The comparison of the preliminary 100 h data for the synthetic doped FHYD catalyst with those of a commercial fixed-bed catalyst pretreated under similar conditions suggests somewhat better catalytic activity of the synthetic doped FHYD than that of the commercial fixed-bed catalyst. The F–T oil and wax obtained as products were characterized extensively using gas chromatography, quantitative 13C NMR, and distortionless enhancement by polarization transfer NMR. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200777v [article] Synthetic doped amorphous ferrihydrite for the fischer – tropsch synthesis of alternative fuels [texte imprimé] / Bali, Sumit, Auteur ; Garima Bali, Auteur ; Frank E. Huggins, Auteur . - 2012 . - pp. 4515–4522. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 12 (Mars 2012) . - pp. 4515–4522 Mots-clés : Ferrihydrites  Oxyhydroxide  minerals Résumé : Ferrihydrites (FHYDs) with the general formula of FeOOH·nH2O are naturally occurring oxyhydroxide minerals found in environments varying from river beds, lakes, and marshes to even living organisms. Here, we report the synthesis of a new kind of synthetic doped amorphous two-line FHYDs containing aluminum and copper, which are not usually known to be found in nature. Transmission electron microscopy carried out on synthetic FHYDs showed them to be amorphous in nature with some nanosized groupings in the form of nanoclusters of about 50–200 nm size without any hint of diffraction fringes associated with crystalline order. The synthetic doped FHYDs exhibit unique properties and have been characterized extensively by magnetic measurements, X-ray diffraction, and electron microscopy as well as by Mössbauer spectroscopic studies. After promotion with potassium, these FHYDs were found to have high activity as catalysts for the Fischer–Tropsch (F–T) conversion of syngas to liquid fuels over a period of 100 h in a fixed bed reactor at 265 °C and 100 psig pressures. The comparison of the preliminary 100 h data for the synthetic doped FHYD catalyst with those of a commercial fixed-bed catalyst pretreated under similar conditions suggests somewhat better catalytic activity of the synthetic doped FHYD than that of the commercial fixed-bed catalyst. The F–T oil and wax obtained as products were characterized extensively using gas chromatography, quantitative 13C NMR, and distortionless enhancement by polarization transfer NMR. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200777v