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Modeling of direct synthesis of hydrogen peroxide in a packed-bed reactor / Teuvo Kilpio in Industrial & engineering chemistry research, Vol. 51 N° 41 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 41 (Octobre 2012) . - pp. 13366–13378 Titre : Modeling of direct synthesis of hydrogen peroxide in a packed-bed reactor Type de document : texte imprimé Auteurs : Teuvo Kilpio, Auteur ; Pierdomenico Biasi, Auteur ; Alice Bittante, Auteur Année de publication : 2012 Article en page(s) : pp. 13366–13378 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Hydrogen  peroxide Résumé : Direct synthesis of hydrogen peroxide from oxygen and hydrogen continues to be a research topic of high interest. It would be most desirable if this synthesis could be carried out in a continuous fixed-bed reactor in a safe way, with a catalyst providing both high selectivity and high productivity. This could significantly simplify the hydrogen peroxide production process and reduce both operating and investment costs. In the conventional anthraquinone-based production process, the hydrogenation and oxidation steps are carried out in separate reactors, and extraction is finally used for hydrogen peroxide recovery. Recirculation of large quantities of the multicomponent organic working solution takes place, and expensive filtration of the hydrogenation catalyst from this vast stream is required when a slurry reactor is used. The main benefit of the conventional process is that it is a well-proven and reliably operating technology. The most straightforward approach for the direct synthesis is to carry out the reaction between H2 and O2 on a heterogeneous catalyst, preferably Pd or Pd/Au catalyst, in a suitable solvent. Methanol is one of the most popular choices for the solvent because the solubilities of H2 and O2 in methanol are much larger than those in water. This article presents a modeling study for the direct synthesis of hydrogen peroxide with methanol as the solvent in a continuous three-phase reactor. The modeling study used data from an experimental study performed with a Pd/CeS catalyst in our laboratory reactor. The aim of the modeling was to provide insight into the physical and chemical phenomena occurring during the process. The reaction system was a challenging one, because both side reaction and decomposition reactions took place simultaneously with the highly desirable synthesis. The model was found to describe the experimental data from the fixed-bed reactor rather well. Particle diffusion was found to be most severe for the synthesis and oxidation reactions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301919y [article] Modeling of direct synthesis of hydrogen peroxide in a packed-bed reactor [texte imprimé] / Teuvo Kilpio, Auteur ; Pierdomenico Biasi, Auteur ; Alice Bittante, Auteur . - 2012 . - pp. 13366–13378. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 41 (Octobre 2012) . - pp. 13366–13378 Mots-clés : Hydrogen  peroxide Résumé : Direct synthesis of hydrogen peroxide from oxygen and hydrogen continues to be a research topic of high interest. It would be most desirable if this synthesis could be carried out in a continuous fixed-bed reactor in a safe way, with a catalyst providing both high selectivity and high productivity. This could significantly simplify the hydrogen peroxide production process and reduce both operating and investment costs. In the conventional anthraquinone-based production process, the hydrogenation and oxidation steps are carried out in separate reactors, and extraction is finally used for hydrogen peroxide recovery. Recirculation of large quantities of the multicomponent organic working solution takes place, and expensive filtration of the hydrogenation catalyst from this vast stream is required when a slurry reactor is used. The main benefit of the conventional process is that it is a well-proven and reliably operating technology. The most straightforward approach for the direct synthesis is to carry out the reaction between H2 and O2 on a heterogeneous catalyst, preferably Pd or Pd/Au catalyst, in a suitable solvent. Methanol is one of the most popular choices for the solvent because the solubilities of H2 and O2 in methanol are much larger than those in water. This article presents a modeling study for the direct synthesis of hydrogen peroxide with methanol as the solvent in a continuous three-phase reactor. The modeling study used data from an experimental study performed with a Pd/CeS catalyst in our laboratory reactor. The aim of the modeling was to provide insight into the physical and chemical phenomena occurring during the process. The reaction system was a challenging one, because both side reaction and decomposition reactions took place simultaneously with the highly desirable synthesis. The model was found to describe the experimental data from the fixed-bed reactor rather well. Particle diffusion was found to be most severe for the synthesis and oxidation reactions. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie301919y

Modeling of a three - phase continuously operating isothermal packed - bed reactor / Teuvo Kilpio 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. 8858-8866 Titre : Modeling of a three - phase continuously operating isothermal packed - bed reactor : Kinetics, mass - transfer, and dispersion effects in the hydrogenation of citral Type de document : texte imprimé Auteurs : Teuvo Kilpio, Auteur ; Paivi Maki-Arvela, Auteur ; Mats Ronnholm, Auteur Année de publication : 2012 Article en page(s) : pp. 8858-8866 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Hydrogenation  Dispersion  Mass  transfer  Kinetics  Fixed  bed  reactor  Modeling Résumé : A continuously operating isothermal dynamic packed-bed reactor was modeled. The model included chemical reaction, gas―liquid mass transfer, convection, axial dispersion, pore diffusion, and catalyst deactivation. The model was solved by using the method of lines. The model was applied on experimental data from citral hydrogenation over a supported nickel catalyst. The experiments had been carried out at 25―65 °C and at 6.1 bar in a laboratory-scale trickle-bed reactor (d = 1 cm; L = 5 cm). The parameters in the model were the rate constants, pore diffusivity, coking rate constant, Pedet number, and gas―liquid mass-transfer coefficient. A sensitivity study was performed to reveal how much a change in each of these changed the product concentration trend. The simulations revealed that the gas―liquid mass-transfer coefficient and effective diffusivity should have been well below expected values to significantly reduce the productivity. The gas-liquid mass transfer and pore diffusion were not rate-limiting; because hydrogen was used in excess, particles were small and the system was dilute. The citral concentration-dependent deactivation model based on site competition was able to describe the observed activity decline. Parameter estimation for the reaction rate and coking rate was carried out. A reasonable agreement with the experimental trends was obtained. An estimate of the Peclet number was obtained from step-response measurements with an inert tracer, which revealed that the reactor did not operate completely as a plug-flow unit. The model described here can be extended to be applicable for other hydrogenation and oxygenation reactions of other fine chemicals. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107440 [article] Modeling of a three - phase continuously operating isothermal packed - bed reactor : Kinetics, mass - transfer, and dispersion effects in the hydrogenation of citral [texte imprimé] / Teuvo Kilpio, Auteur ; Paivi Maki-Arvela, Auteur ; Mats Ronnholm, Auteur . - 2012 . - pp. 8858-8866. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 8858-8866 Mots-clés : Hydrogenation  Dispersion  Mass  transfer  Kinetics  Fixed  bed  reactor  Modeling Résumé : A continuously operating isothermal dynamic packed-bed reactor was modeled. The model included chemical reaction, gas―liquid mass transfer, convection, axial dispersion, pore diffusion, and catalyst deactivation. The model was solved by using the method of lines. The model was applied on experimental data from citral hydrogenation over a supported nickel catalyst. The experiments had been carried out at 25―65 °C and at 6.1 bar in a laboratory-scale trickle-bed reactor (d = 1 cm; L = 5 cm). The parameters in the model were the rate constants, pore diffusivity, coking rate constant, Pedet number, and gas―liquid mass-transfer coefficient. A sensitivity study was performed to reveal how much a change in each of these changed the product concentration trend. The simulations revealed that the gas―liquid mass-transfer coefficient and effective diffusivity should have been well below expected values to significantly reduce the productivity. The gas-liquid mass transfer and pore diffusion were not rate-limiting; because hydrogen was used in excess, particles were small and the system was dilute. The citral concentration-dependent deactivation model based on site competition was able to describe the observed activity decline. Parameter estimation for the reaction rate and coking rate was carried out. A reasonable agreement with the experimental trends was obtained. An estimate of the Peclet number was obtained from step-response measurements with an inert tracer, which revealed that the reactor did not operate completely as a plug-flow unit. The model described here can be extended to be applicable for other hydrogenation and oxygenation reactions of other fine chemicals. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107440