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Chemocatalytic oxidation of lactose to lactobionic acid over Pd−Bi/SBA-15: reaction kinetics and modeling / Khaled Belkacemi 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 6878–6889 Titre : Chemocatalytic oxidation of lactose to lactobionic acid over Pd−Bi/SBA-15: reaction kinetics and modeling Type de document : texte imprimé Auteurs : Khaled Belkacemi, Auteur ; Safia Hamoudi, Auteur Année de publication : 2010 Article en page(s) : pp 6878–6889 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Chemocatalytic  oxidation  Reaction  kinetics. Résumé : Lactobionic acid (LBA) was synthesized from the direct aerobic oxidation of lactose under a very low O2 concentration with high conversion (96%) and 100% selectivity over low loadings (1.02−0.64%) of bimetallic Pd−Bi supported on mesoporous SBA-15 silica material. Under alkaline conditions (pH 9), the catalyst exhibited enhanced activity and stability with unprecedented complete selectivity toward LBA formation. Furthermore, it exhibited pretty good stability toward metal leaching. It was observed that, with a selective deposition of bismuth on palladium, as well as adequate alkaline pH processing, the redox reaction chain performed efficiently and maintained the continuous dehydrogenation of lactose, while avoiding poisoning of the Pd−Bi bimetallic catalyst. Using the Langmuir−Hinshelwood−Hougen−Watson approach, a kinetic model was developed to predict the fates of the lactose and LBA. The rate equation of lactose consumption contains Langmuir adsorption terms, which accounts for the competitive reversible dissociative chemisorption of oxygen and for the reversible associative adsorption of lactose. The kinetic model was verified by comparing the experimental results with those foreseen in the simulation for different experimental conditions. The assessment of the determined Arrhenius parameters led to physically meaningful estimates of activation energy. The Langmuir adsorption isotherms are physically meaningful, where the standard entropy and enthalpy of adsorption were shown to fulfill established guidelines, which assesses the physical sense of their values. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901724j [article] Chemocatalytic oxidation of lactose to lactobionic acid over Pd−Bi/SBA-15: reaction kinetics and modeling [texte imprimé] / Khaled Belkacemi, Auteur ; Safia Hamoudi, Auteur . - 2010 . - pp 6878–6889. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 15 (Août 2010) . - pp 6878–6889 Mots-clés : Chemocatalytic  oxidation  Reaction  kinetics. Résumé : Lactobionic acid (LBA) was synthesized from the direct aerobic oxidation of lactose under a very low O2 concentration with high conversion (96%) and 100% selectivity over low loadings (1.02−0.64%) of bimetallic Pd−Bi supported on mesoporous SBA-15 silica material. Under alkaline conditions (pH 9), the catalyst exhibited enhanced activity and stability with unprecedented complete selectivity toward LBA formation. Furthermore, it exhibited pretty good stability toward metal leaching. It was observed that, with a selective deposition of bismuth on palladium, as well as adequate alkaline pH processing, the redox reaction chain performed efficiently and maintained the continuous dehydrogenation of lactose, while avoiding poisoning of the Pd−Bi bimetallic catalyst. Using the Langmuir−Hinshelwood−Hougen−Watson approach, a kinetic model was developed to predict the fates of the lactose and LBA. The rate equation of lactose consumption contains Langmuir adsorption terms, which accounts for the competitive reversible dissociative chemisorption of oxygen and for the reversible associative adsorption of lactose. The kinetic model was verified by comparing the experimental results with those foreseen in the simulation for different experimental conditions. The assessment of the determined Arrhenius parameters led to physically meaningful estimates of activation energy. The Langmuir adsorption isotherms are physically meaningful, where the standard entropy and enthalpy of adsorption were shown to fulfill established guidelines, which assesses the physical sense of their values. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901724j

Low trans and saturated vegetable oil hydrogenation over nanostructured Pd/silica catalysts / Khaled Belkacemi in Industrial & engineering chemistry research, Vol. 48 N°3 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°3 (Février 2009) . - p. 1081–1089 Titre : Low trans and saturated vegetable oil hydrogenation over nanostructured Pd/silica catalysts : process parameters and mass-transfer features effects Type de document : texte imprimé Auteurs : Khaled Belkacemi, Auteur ; Safia Hamoudi, Auteur Année de publication : 2009 Article en page(s) : p. 1081–1089 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Catalytic  hydogenation  Pd  catalyst  Hydogenation  Vegetable  oils Résumé : Sunflower and canola oils were hydrogenated over a novel Pd catalyst and a commercial N catalyst. The Pd catalyst consisted of palladium nanoparticles highly dispersed on mesostructured silica material. The effect of temperature (80−130 °C) and H2 pressure (3.6−9.3 atm) on the activity, selectivity, and trans (TFA) and saturated (SFA) fatty acids formation were studied for both oils and types of catalysts. It was found that the reaction temperature and the hydrogen pressure increased the activity of both catalysts and controlled the solubility of hydrogen and the cis/trans isomerization. The Pd catalyst exhibited a greater selectivity toward the formation of monoene in comparison to the commercial Ni catalyst. Partial hydrogenation of both oils from initial iodine (IVo) value of 120−130 to a final IV of 90 with the nanostructured Pd catalyst using a conventional stirred reactor equipped with a surface aeration turbine-type impeller yielded modified oils with low TFA level (7−10%) and also controlled the formation SFA (∼7%) under mild process conditions. Further reduction of TFA level was achieved when the hydrogenation of vegetable oils over Pd catalyst was carried out with a reactor equipped with a gas-inducing sparger-type impeller having enhanced mass-transfer features. Very low TFA (<5%) and SFA (3%) levels were obtained at a final IV value of 92. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800559v [article] Low trans and saturated vegetable oil hydrogenation over nanostructured Pd/silica catalysts : process parameters and mass-transfer features effects [texte imprimé] / Khaled Belkacemi, Auteur ; Safia Hamoudi, Auteur . - 2009 . - p. 1081–1089. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°3 (Février 2009) . - p. 1081–1089 Mots-clés : Catalytic  hydogenation  Pd  catalyst  Hydogenation  Vegetable  oils Résumé : Sunflower and canola oils were hydrogenated over a novel Pd catalyst and a commercial N catalyst. The Pd catalyst consisted of palladium nanoparticles highly dispersed on mesostructured silica material. The effect of temperature (80−130 °C) and H2 pressure (3.6−9.3 atm) on the activity, selectivity, and trans (TFA) and saturated (SFA) fatty acids formation were studied for both oils and types of catalysts. It was found that the reaction temperature and the hydrogen pressure increased the activity of both catalysts and controlled the solubility of hydrogen and the cis/trans isomerization. The Pd catalyst exhibited a greater selectivity toward the formation of monoene in comparison to the commercial Ni catalyst. Partial hydrogenation of both oils from initial iodine (IVo) value of 120−130 to a final IV of 90 with the nanostructured Pd catalyst using a conventional stirred reactor equipped with a surface aeration turbine-type impeller yielded modified oils with low TFA level (7−10%) and also controlled the formation SFA (∼7%) under mild process conditions. Further reduction of TFA level was achieved when the hydrogenation of vegetable oils over Pd catalyst was carried out with a reactor equipped with a gas-inducing sparger-type impeller having enhanced mass-transfer features. Very low TFA (<5%) and SFA (3%) levels were obtained at a final IV value of 92. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800559v

Solution asymptotiquement presque périodiques des équations différentielles fonctionnelles / Khaled Belkacemi 

Public ISBD Titre : Solution asymptotiquement presque périodiques des équations différentielles fonctionnelles Type de document : texte imprimé Auteurs : Khaled Belkacemi, Auteur ; El-Kolli, Amar, Directeur de thèse Editeur : Université des Sciences et de la Technologie Houari Boumedienne Année de publication : 1983 Importance : 85 f. Format : 27 cm. Note générale : Mémoire de Magister : Mathématique : Alger, Université des Sciences et de la Technologie Houari Boumediene : 1983 Bibliogr. f. 86 - 88 Langues : Français (fre) Mots-clés : Équation  --  différentielle  --  fonctionnelle  ;  Mouvement  --  asymptotique  --  stable  ;  Équation  --  opérationnelle  ;  Stabilité  asymptotique  ;  Solution  --  asymptotique  --  presque-périodique Index. décimale : M002383 Résumé : Dans ce travail, on étudie le problème de l'existence des solutions asymptotiquement presque-périodique pour l'équation différentielle fonctionnelle. Comme pour les cas des équations différentielles non-autonomes, on construit des systèmes dynamiques de translation respectivement sur l'espace des seconds membres Y et sur l'espace des solutions Z. Solution asymptotiquement presque périodiques des équations différentielles fonctionnelles [texte imprimé] / Khaled Belkacemi, Auteur ; El-Kolli, Amar, Directeur de thèse . - Alger : Université des Sciences et de la Technologie Houari Boumedienne, 1983 . - 85 f. ; 27 cm. Mémoire de Magister : Mathématique : Alger, Université des Sciences et de la Technologie Houari Boumediene : 1983 Bibliogr. f. 86 - 88 Langues : Français (fre) Mots-clés : Équation  --  différentielle  --  fonctionnelle  ;  Mouvement  --  asymptotique  --  stable  ;  Équation  --  opérationnelle  ;  Stabilité  asymptotique  ;  Solution  --  asymptotique  --  presque-périodique Index. décimale : M002383 Résumé : Dans ce travail, on étudie le problème de l'existence des solutions asymptotiquement presque-périodique pour l'équation différentielle fonctionnelle. Comme pour les cas des équations différentielles non-autonomes, on construit des systèmes dynamiques de translation respectivement sur l'espace des seconds membres Y et sur l'espace des solutions Z.

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