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Effect of synthesis conditions on the structure and catalytic performance of V- and Ce-incorporated SBA-15-like materials in propane selective oxidation / Ozge Aktas 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 6790–6802 Titre : Effect of synthesis conditions on the structure and catalytic performance of V- and Ce-incorporated SBA-15-like materials in propane selective oxidation Type de document : texte imprimé Auteurs : Ozge Aktas, Auteur ; Sena Yasyerli, Auteur ; Gulsen Dogu, Auteur Année de publication : 2010 Article en page(s) : pp 6790–6802 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalyst  Selective  Oxidation. Résumé : Vanadia- and/or ceria-incorporated SBA-15-like materials were prepared by impregnation and one-pot hydrothermal synthesis procedures at different solution pH values. The pH of the synthesis solution was found to have a very strong effect on the pore structure, chemical composition, and morphology of the synthesized materials. Materials synthesized by impregnation of V and/or Ce and by the one-pot hydrothermal route at pH 1.0 showed the characteristic ordered pore structure of SBA-15. However, the materials prepared by the one-pot synthesis route at pH 1.5 gave complex pore structures with bottleneck-shaped and/or slit-like interconnected pores. Activity tests in the selective oxidation of propane showed higher activities for the V-incorporated materials than for the materials containing Ce and V−Ce. Catalysts synthesized by impregnation gave higher propane conversions. However, the propylene selectivity values were higher with the catalysts prepared by the one-pot route. An increase in the temperature from 550 to 600 °C led to increases in both the conversion and the propylene selectivity with the V- and V−Ce-incorporated materials prepared by the one-pot procedure at pH 1.5. For the V-incorporated catalyst prepared by this route, the propane conversion and propylene selectivity were obtained as 40% and 62%, respectively, at a space time of 0.4 s·g·cm−3 and a temperature of 600 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901672b [article] Effect of synthesis conditions on the structure and catalytic performance of V- and Ce-incorporated SBA-15-like materials in propane selective oxidation [texte imprimé] / Ozge Aktas, Auteur ; Sena Yasyerli, Auteur ; Gulsen Dogu, Auteur . - 2010 . - pp 6790–6802. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6790–6802 Mots-clés : Catalyst  Selective  Oxidation. Résumé : Vanadia- and/or ceria-incorporated SBA-15-like materials were prepared by impregnation and one-pot hydrothermal synthesis procedures at different solution pH values. The pH of the synthesis solution was found to have a very strong effect on the pore structure, chemical composition, and morphology of the synthesized materials. Materials synthesized by impregnation of V and/or Ce and by the one-pot hydrothermal route at pH 1.0 showed the characteristic ordered pore structure of SBA-15. However, the materials prepared by the one-pot synthesis route at pH 1.5 gave complex pore structures with bottleneck-shaped and/or slit-like interconnected pores. Activity tests in the selective oxidation of propane showed higher activities for the V-incorporated materials than for the materials containing Ce and V−Ce. Catalysts synthesized by impregnation gave higher propane conversions. However, the propylene selectivity values were higher with the catalysts prepared by the one-pot route. An increase in the temperature from 550 to 600 °C led to increases in both the conversion and the propylene selectivity with the V- and V−Ce-incorporated materials prepared by the one-pot procedure at pH 1.5. For the V-incorporated catalyst prepared by this route, the propane conversion and propylene selectivity were obtained as 40% and 62%, respectively, at a space time of 0.4 s·g·cm−3 and a temperature of 600 °C. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901672b

Effects of sorption enhancement and isobutene formation on etherification of glycerol with tert - butyl alcohol in a flow reactor / Nalan Ozbay 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. 8788–8795 Titre : Effects of sorption enhancement and isobutene formation on etherification of glycerol with tert - butyl alcohol in a flow reactor Type de document : texte imprimé Auteurs : Nalan Ozbay, Auteur ; Nuray Oktar, Auteur ; Gulsen Dogu, Auteur Année de publication : 2012 Article en page(s) : pp. 8788–8795 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Isobutene  Glycerol  Flow  reactor Résumé : In the presented work, liquid phase etherification reaction of glycerol (G) with tert-butyl alcohol (TBA) was investigated in a continuous flow reactor using Amberlyst-15 (A-15) as the catalyst. Some experiments were also repeated in a batch reactor at autogenous pressure. Effects of feed composition, reaction temperature (70–110 °C), and reaction pressure (1–5 bar) on the product distribution were investigated. When flow reactor pressure was reduced from 5 to 1 bar, enhanced glycerol conversion and isobutene formation were observed. Conversion of glycerol reached 66% at 110 °C, at a space time of 18 s·g·cm–3. However, batch reactor results indicated glycerol conversion values over 90% with diether selectivity of about 36% at much longer reaction times, over 400 min. Results indicated significance of equilibrium limitations, which initiated the idea of performing sorption enhanced reaction experiments in the flow reactor using Zeolite 4A and 5A as water adsorbents. Results of these sorption enhanced reactor experiments proved significant enhancement of glycerol conversion and diether yield by in situ removal of produced water during the etherification reaction. Among these two adsorbents, performance of Zeolite 4A was better. Diether selectivity increased from about 0.20 to values over 0.33 in the sorption enhanced reactor experiments performed with a zeolite/catalyst ratio of 4/1 at 90 °C. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201720q [article] Effects of sorption enhancement and isobutene formation on etherification of glycerol with tert - butyl alcohol in a flow reactor [texte imprimé] / Nalan Ozbay, Auteur ; Nuray Oktar, Auteur ; Gulsen Dogu, Auteur . - 2012 . - pp. 8788–8795. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8788–8795 Mots-clés : Isobutene  Glycerol  Flow  reactor Résumé : In the presented work, liquid phase etherification reaction of glycerol (G) with tert-butyl alcohol (TBA) was investigated in a continuous flow reactor using Amberlyst-15 (A-15) as the catalyst. Some experiments were also repeated in a batch reactor at autogenous pressure. Effects of feed composition, reaction temperature (70–110 °C), and reaction pressure (1–5 bar) on the product distribution were investigated. When flow reactor pressure was reduced from 5 to 1 bar, enhanced glycerol conversion and isobutene formation were observed. Conversion of glycerol reached 66% at 110 °C, at a space time of 18 s·g·cm–3. However, batch reactor results indicated glycerol conversion values over 90% with diether selectivity of about 36% at much longer reaction times, over 400 min. Results indicated significance of equilibrium limitations, which initiated the idea of performing sorption enhanced reaction experiments in the flow reactor using Zeolite 4A and 5A as water adsorbents. Results of these sorption enhanced reactor experiments proved significant enhancement of glycerol conversion and diether yield by in situ removal of produced water during the etherification reaction. Among these two adsorbents, performance of Zeolite 4A was better. Diether selectivity increased from about 0.20 to values over 0.33 in the sorption enhanced reactor experiments performed with a zeolite/catalyst ratio of 4/1 at 90 °C. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201720q

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