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Improved Procedure for Hydrogen Peroxide Production by Oxidation of Secondary Alcohols and Oxygenated Cosolvents† / pilsar de Fruto Escrig 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.8025–8031 Titre : Improved Procedure for Hydrogen Peroxide Production by Oxidation of Secondary Alcohols and Oxygenated Cosolvents† Type de document : texte imprimé Auteurs : pilsar de Fruto Escrig, Auteur ; Alvaro garriga meco, Auteur ; ana padilla polo, Auteur Année de publication : 2008 Article en page(s) : p.8025–8031 Note générale : Chemical engineering Langues : Anglais (eng) Résumé : An improved procedure for the production of hydrogen peroxide via oxidation, with molecular oxygen, of secondary alcohols admixed with oxygenated co-solvents as primary alcohols and/or ether has been studied. The selectivity, conversion, and rates have been increased, in comparison to the data obtained in the absence of co-solvents. The increase observed in the oxidation rate of 1-phenylethanol in the presence of co-solvents has been interpreted using the chain co-oxidation reaction theory. The relative values of the termination constants of 1-phenylethanol and the tested co-solvents have been estimated. The lowest values of the termination constant of the peroxy radicals derived from the co-solvents explain the increase in the steady concentration of free radicals in the reaction media and, consequently, the enhancement observed in the co-oxidation rates. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800159u [article] Improved Procedure for Hydrogen Peroxide Production by Oxidation of Secondary Alcohols and Oxygenated Cosolvents† [texte imprimé] / pilsar de Fruto Escrig, Auteur ; Alvaro garriga meco, Auteur ; ana padilla polo, Auteur . - 2008 . - p.8025–8031. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p.8025–8031 Résumé : An improved procedure for the production of hydrogen peroxide via oxidation, with molecular oxygen, of secondary alcohols admixed with oxygenated co-solvents as primary alcohols and/or ether has been studied. The selectivity, conversion, and rates have been increased, in comparison to the data obtained in the absence of co-solvents. The increase observed in the oxidation rate of 1-phenylethanol in the presence of co-solvents has been interpreted using the chain co-oxidation reaction theory. The relative values of the termination constants of 1-phenylethanol and the tested co-solvents have been estimated. The lowest values of the termination constant of the peroxy radicals derived from the co-solvents explain the increase in the steady concentration of free radicals in the reaction media and, consequently, the enhancement observed in the co-oxidation rates. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800159u

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