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Nafion-incorporated silicate structured nanocomposite mesoporous catalysts for dimethyl ether synthesis / Aysegul Ciftci in Industrial & engineering chemistry research, Vol. 49 N° 15 (Août 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6753–6762 Titre : Nafion-incorporated silicate structured nanocomposite mesoporous catalysts for dimethyl ether synthesis Type de document : texte imprimé Auteurs : Aysegul Ciftci, Auteur ; Naime Asli Sezgi, Auteur ; Timur Dogu, Auteur Année de publication : 2010 Article en page(s) : pp 6753–6762 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Mesoporous  Catalysts  Ether  synthesis. Résumé : Being chemically and thermally stable, Nafion resin is considered to be an attractive solid acid catalyst. Although it has high acid strength and the ability to catalyze a wide range of reactions, the catalytic activity of Nafion is limited, because of its very low specific surface area. In this study, mesoporous Nafion−silica nanocomposites were developed by following a one-pot acidic hydrothermal synthesis procedure. Synthesized catalysts were determined to have well-dispersed structures with high surface area values (595−792 m2/g) and strong Brønsted, as well as Lewis, acid sites. The activities of these novel catalysts were tested in dimethyl ether synthesis from methanol in a flow system. The effects of modifications in the synthesis procedure and Nafion loading showed that the material synthesized from a solution containing a Nafion/silica weight ratio of 0.15 and refluxed with a 2 M sulfuric acid−ethanol (SAE) mixture for surfactant removal was the best catalyst for this reaction. Production of the green transportation fuel alternate dimethyl ether (DME) was achieved with this catalyst at very high yields with almost 100% DME selectivity at >180 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9015667 [article] Nafion-incorporated silicate structured nanocomposite mesoporous catalysts for dimethyl ether synthesis [texte imprimé] / Aysegul Ciftci, Auteur ; Naime Asli Sezgi, Auteur ; Timur Dogu, Auteur . - 2010 . - pp 6753–6762. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6753–6762 Mots-clés : Mesoporous  Catalysts  Ether  synthesis. Résumé : Being chemically and thermally stable, Nafion resin is considered to be an attractive solid acid catalyst. Although it has high acid strength and the ability to catalyze a wide range of reactions, the catalytic activity of Nafion is limited, because of its very low specific surface area. In this study, mesoporous Nafion−silica nanocomposites were developed by following a one-pot acidic hydrothermal synthesis procedure. Synthesized catalysts were determined to have well-dispersed structures with high surface area values (595−792 m2/g) and strong Brønsted, as well as Lewis, acid sites. The activities of these novel catalysts were tested in dimethyl ether synthesis from methanol in a flow system. The effects of modifications in the synthesis procedure and Nafion loading showed that the material synthesized from a solution containing a Nafion/silica weight ratio of 0.15 and refluxed with a 2 M sulfuric acid−ethanol (SAE) mixture for surfactant removal was the best catalyst for this reaction. Production of the green transportation fuel alternate dimethyl ether (DME) was achieved with this catalyst at very high yields with almost 100% DME selectivity at >180 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9015667

Novel mesoporous nanocomposite WOx-silicate acidic catalysts / Dilek Varisli in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9394–9401 Titre : Novel mesoporous nanocomposite WOx-silicate acidic catalysts : ethylene and diethylether from ethanol Type de document : texte imprimé Auteurs : Dilek Varisli, Auteur ; Timur Dogu, Auteur ; Gulsen Dogu, Auteur Année de publication : 2010 Article en page(s) : pp. 9394–9401 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solid  acid  catalysts  Ethylene  Diethylether  Ethanol Résumé : Solid acid catalysts are extensively used in a number of industrially important catalytic reactions. Here, water-insoluble novel mesoporous solid acid catalysts, with a unique structure composed of WOx nanorods and W nanoballs within an amorphous silicate lattice, were synthesized following a one-pot hydrothermal route, using silicotungstic acid (STA) as the active component. Surface area of these catalysts are more than 2 orders of magnitude higher than that of pure STA, and they showed very high activity for the simultaneous production of ethylene and diethylether (DEE), which is an attractive transportation fuel alternate, from a nonpetroleum feedstock, namely ethanol. Depending upon the operating conditions, ethylene or DEE selectivities approaching 1.0 or 0.8 were obtained, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8008154 [article] Novel mesoporous nanocomposite WOx-silicate acidic catalysts : ethylene and diethylether from ethanol [texte imprimé] / Dilek Varisli, Auteur ; Timur Dogu, Auteur ; Gulsen Dogu, Auteur . - 2010 . - pp. 9394–9401. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9394–9401 Mots-clés : Solid  acid  catalysts  Ethylene  Diethylether  Ethanol Résumé : Solid acid catalysts are extensively used in a number of industrially important catalytic reactions. Here, water-insoluble novel mesoporous solid acid catalysts, with a unique structure composed of WOx nanorods and W nanoballs within an amorphous silicate lattice, were synthesized following a one-pot hydrothermal route, using silicotungstic acid (STA) as the active component. Surface area of these catalysts are more than 2 orders of magnitude higher than that of pure STA, and they showed very high activity for the simultaneous production of ethylene and diethylether (DEE), which is an attractive transportation fuel alternate, from a nonpetroleum feedstock, namely ethanol. Depending upon the operating conditions, ethylene or DEE selectivities approaching 1.0 or 0.8 were obtained, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8008154

Silicotungstic acid impregnated MCM-41-like mesoporous solid acid catalysts for dehydration of ethanol / Dilek Varisli in Industrial & engineering chemistry research, Vol. 47 n°12 (Juin 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4071–4076 Titre : Silicotungstic acid impregnated MCM-41-like mesoporous solid acid catalysts for dehydration of ethanol Type de document : texte imprimé Auteurs : Dilek Varisli, Auteur ; Timur Dogu, Auteur ; Gulsen Dogu, Auteur Année de publication : 2008 Article en page(s) : p. 4071–4076 Note générale : Bibliogr. p. 4076 Langues : Anglais (eng) Mots-clés : Mesoporous  solid  acid;  Impregnation;  Ethanol  dehydration Résumé : In this study, mesoporous nanocomposite silicotungstic acid (STA) incorporated MCM-41 and mesoporous aluminosilicate catalysts with narrow pore size distributions, in the range of 2.5–3.5 nm, were successfully synthesized following different impregnation procedures. Results showed that the catalyst preparation procedure had significant influence on its activity as well as the product distribution in ethanol dehydration. STAMCM41C catalyst, which was prepared by the impregnation of STA into calcined MCM-41 containing a W/Si ratio of 0.24, and STAMAS catalyst, which was prepared by the impregnation of STA into mesoporous aluminosilicate, showed very high activities in dehydration of ethanol. Ethylene yield showed an increasing trend with temperature, reaching to about 100% above 250 °C. In contrast to ethylene, DEE was formed at lower temperatures, reaching to a yield value of about 70% at 180 °C with STAMCM41C. DEE formation at lower temperatures was concluded to be due to the presence of Bronsted acid sites of this catalyst. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800192t [article] Silicotungstic acid impregnated MCM-41-like mesoporous solid acid catalysts for dehydration of ethanol [texte imprimé] / Dilek Varisli, Auteur ; Timur Dogu, Auteur ; Gulsen Dogu, Auteur . - 2008 . - p. 4071–4076. Bibliogr. p. 4076 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4071–4076 Mots-clés : Mesoporous  solid  acid;  Impregnation;  Ethanol  dehydration Résumé : In this study, mesoporous nanocomposite silicotungstic acid (STA) incorporated MCM-41 and mesoporous aluminosilicate catalysts with narrow pore size distributions, in the range of 2.5–3.5 nm, were successfully synthesized following different impregnation procedures. Results showed that the catalyst preparation procedure had significant influence on its activity as well as the product distribution in ethanol dehydration. STAMCM41C catalyst, which was prepared by the impregnation of STA into calcined MCM-41 containing a W/Si ratio of 0.24, and STAMAS catalyst, which was prepared by the impregnation of STA into mesoporous aluminosilicate, showed very high activities in dehydration of ethanol. Ethylene yield showed an increasing trend with temperature, reaching to about 100% above 250 °C. In contrast to ethylene, DEE was formed at lower temperatures, reaching to a yield value of about 70% at 180 °C with STAMCM41C. DEE formation at lower temperatures was concluded to be due to the presence of Bronsted acid sites of this catalyst. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800192t

Sorption - enhanced reforming of ethanol over Ni - and Co - incorporated MCM - 41 type catalysts / Seval Gunduz in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8796–8805 Titre : Sorption - enhanced reforming of ethanol over Ni - and Co - incorporated MCM - 41 type catalysts Type de document : texte imprimé Auteurs : Seval Gunduz, Auteur ; Timur Dogu, Auteur Année de publication : 2012 Article en page(s) : pp. 8796–8805 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Sorption  Ethanol  Catalysts Résumé : Ni- and Co-incorporated MCM-41 type mesoporous materials with Ni/Si and Co/Si molar ratios of 0.12 were synthesized, characterized, and tested in both steam reforming of ethanol (SRE) and sorption-enhanced steam reforming of ethanol (SESRE) reactions. Characterization results showed that Co and Ni were successfully incorporated and well-dispersed in the mesoporous MCM-41 support. Ni- and Co-incorporated MCM-41 catalysts had surface area values of 449.0 and 303.6 m2/g, respectively. They also had narrow pore size distributions, with average pore diameters of 2.2 and 1.98 nm, respectively. SESRE results obtained with these catalysts showed that in situ capture of CO2 during ethanol reforming reaction significantly enhanced hydrogen yield in the temperature range of 500–600 °C. The catalytic performance of Ni-incorporated MCM-41 was much better than the Co-incorporated MCM-41, in hydrogen production by ethanol reforming. The highest hydrogen yield value obtained over the Ni-incorporated MCM-41 catalyst was achieved at 600 °C as 5.6 in SESRE reaction. This was 94% of the maximum possible hydrogen yield value of 6.0. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201852f [article] Sorption - enhanced reforming of ethanol over Ni - and Co - incorporated MCM - 41 type catalysts [texte imprimé] / Seval Gunduz, Auteur ; Timur Dogu, Auteur . - 2012 . - pp. 8796–8805. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8796–8805 Mots-clés : Sorption  Ethanol  Catalysts Résumé : Ni- and Co-incorporated MCM-41 type mesoporous materials with Ni/Si and Co/Si molar ratios of 0.12 were synthesized, characterized, and tested in both steam reforming of ethanol (SRE) and sorption-enhanced steam reforming of ethanol (SESRE) reactions. Characterization results showed that Co and Ni were successfully incorporated and well-dispersed in the mesoporous MCM-41 support. Ni- and Co-incorporated MCM-41 catalysts had surface area values of 449.0 and 303.6 m2/g, respectively. They also had narrow pore size distributions, with average pore diameters of 2.2 and 1.98 nm, respectively. SESRE results obtained with these catalysts showed that in situ capture of CO2 during ethanol reforming reaction significantly enhanced hydrogen yield in the temperature range of 500–600 °C. The catalytic performance of Ni-incorporated MCM-41 was much better than the Co-incorporated MCM-41, in hydrogen production by ethanol reforming. The highest hydrogen yield value obtained over the Ni-incorporated MCM-41 catalyst was achieved at 600 °C as 5.6 in SESRE reaction. This was 94% of the maximum possible hydrogen yield value of 6.0. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201852f