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New Two-Step Process for Propene Oxide Production (HPPO) Based on the Direct Synthesis of Hydrogen Peroxide / Gema Blanco-Brieva in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8011–8015 Titre : New Two-Step Process for Propene Oxide Production (HPPO) Based on the Direct Synthesis of Hydrogen Peroxide Type de document : texte imprimé Auteurs : Gema Blanco-Brieva, Auteur ; M.carmen capel sanchez, Auteur ; M.pilar de frutos, Auteur ; ana padilla polo, Auteur Année de publication : 2008 Article en page(s) : p. 8011–8015 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : oxide  production  -Aqueous  solutions Résumé : In previous papers, we showed that (i) neutral solutions of hydrogen peroxide can be safely obtained by the direct reaction of H2 and O2 gas mixtures in the presence of Pd-loaded sulfonic acid resins and (ii) low molecular weight olefins can be successfully epoxidized using aqueous solutions of H2O2 in the presence of amorphous Ti/SiO2 catalysts. Against this background, this paper seeks to go one step further in our on-site H2O2 strategy by combining the direct synthesis of nonacidic H2O2 solutions with the catalyzed epoxidation of alkenes with hydrogen peroxide. In a first step, we optimized the reaction conditions for the direct synthesis of H2O2 working in a semibatch reactor. Aqueous solutions of 9 wt % H2O2 were then used in the epoxidation of oct-1-ene on a Ti-loaded amorphous silica catalyst, and reaction conditions were optimized. Finally, the propene epoxidation reaction was conducted in a continuous mode under the optimum reaction conditions selected (343 K, H2O2/catalyst ratio = 1:4, propene/catalyst ratio = 25, residence time 45 min). At steady-state, the conversion level of H2O2 reached 96% with a selectivity of hydrogen peroxide to propene oxide of 95%. After 135 h of reaction time, a slight decrease in the selectivity of H2O2 to epoxide was observed, with a decrease of H2O2 conversion from 96 to 80%. This catalyst deactivation is reversible, as original activity is fully recovered upon regeneration in air at 873 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800245r [article] New Two-Step Process for Propene Oxide Production (HPPO) Based on the Direct Synthesis of Hydrogen Peroxide [texte imprimé] / Gema Blanco-Brieva, Auteur ; M.carmen capel sanchez, Auteur ; M.pilar de frutos, Auteur ; ana padilla polo, Auteur . - 2008 . - p. 8011–8015. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8011–8015 Mots-clés : oxide  production  -Aqueous  solutions Résumé : In previous papers, we showed that (i) neutral solutions of hydrogen peroxide can be safely obtained by the direct reaction of H2 and O2 gas mixtures in the presence of Pd-loaded sulfonic acid resins and (ii) low molecular weight olefins can be successfully epoxidized using aqueous solutions of H2O2 in the presence of amorphous Ti/SiO2 catalysts. Against this background, this paper seeks to go one step further in our on-site H2O2 strategy by combining the direct synthesis of nonacidic H2O2 solutions with the catalyzed epoxidation of alkenes with hydrogen peroxide. In a first step, we optimized the reaction conditions for the direct synthesis of H2O2 working in a semibatch reactor. Aqueous solutions of 9 wt % H2O2 were then used in the epoxidation of oct-1-ene on a Ti-loaded amorphous silica catalyst, and reaction conditions were optimized. Finally, the propene epoxidation reaction was conducted in a continuous mode under the optimum reaction conditions selected (343 K, H2O2/catalyst ratio = 1:4, propene/catalyst ratio = 25, residence time 45 min). At steady-state, the conversion level of H2O2 reached 96% with a selectivity of hydrogen peroxide to propene oxide of 95%. After 135 h of reaction time, a slight decrease in the selectivity of H2O2 to epoxide was observed, with a decrease of H2O2 conversion from 96 to 80%. This catalyst deactivation is reversible, as original activity is fully recovered upon regeneration in air at 873 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800245r

Preparation characterization, and acidity evaluation of perfluorosulfonic acid-functionalized silica catalysts / Gema Blanco-Brieva in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8005-8010 Titre : Preparation characterization, and acidity evaluation of perfluorosulfonic acid-functionalized silica catalysts Type de document : texte imprimé Auteurs : Gema Blanco-Brieva, Auteur ; Jose M. Campos Martin, Auteur Année de publication : 2008 Article en page(s) : p. 8005-8010 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Solid  acid  catalysts  perfluorsulfonic  acid  xps  technique Résumé : Three different hybrid organic/inorganic solid acid catalysts were prepared by grafting perfluorosulfonic acid onto amorphous silica gel by covalently anchoring β-sultone onto the hydroxyl groups on the silica surface. The anchored sulfonic groups have been characterized by thermal analysis, infrared spectroscopy, and photoelectron spectroscopy (XPS). Particularly, the XPS technique has proven to be an extremely powerful tool to determine the nature and chemical state of sulfur and carbon, as well as the surface density of the acid groups. The hybrid organic/inorganic systems functionalized with sulfonic acid groups were tested in the esterification reaction of acetic acid with methanol in liquid phase. Activity results obtained at 333 K and using an initial molar ratio AcOOH:MeOH = 1:1 revealed that the acid-functionalized, nonsilylated catalyst reaches acetic acid conversion of ∼50%, which contrasts with the much lower level (∼30%) reached by a commercial Nafion silica composite sample. Treatment of the catalysts in methanol at 333 K under stirring for 48 h emphasized that only the acid-functionalized and silylated sample retains some of the sulfonic groups. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800221f [article] Preparation characterization, and acidity evaluation of perfluorosulfonic acid-functionalized silica catalysts [texte imprimé] / Gema Blanco-Brieva, Auteur ; Jose M. Campos Martin, Auteur . - 2008 . - p. 8005-8010. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8005-8010 Mots-clés : Solid  acid  catalysts  perfluorsulfonic  acid  xps  technique Résumé : Three different hybrid organic/inorganic solid acid catalysts were prepared by grafting perfluorosulfonic acid onto amorphous silica gel by covalently anchoring β-sultone onto the hydroxyl groups on the silica surface. The anchored sulfonic groups have been characterized by thermal analysis, infrared spectroscopy, and photoelectron spectroscopy (XPS). Particularly, the XPS technique has proven to be an extremely powerful tool to determine the nature and chemical state of sulfur and carbon, as well as the surface density of the acid groups. The hybrid organic/inorganic systems functionalized with sulfonic acid groups were tested in the esterification reaction of acetic acid with methanol in liquid phase. Activity results obtained at 333 K and using an initial molar ratio AcOOH:MeOH = 1:1 revealed that the acid-functionalized, nonsilylated catalyst reaches acetic acid conversion of ∼50%, which contrasts with the much lower level (∼30%) reached by a commercial Nafion silica composite sample. Treatment of the catalysts in methanol at 333 K under stirring for 48 h emphasized that only the acid-functionalized and silylated sample retains some of the sulfonic groups. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800221f