Documents disponibles écrits par cet auteur

Activity and selectivity of nanostructured sulfur-doped Pd/SBA-15 catalyst for vegetable oil hardening / Nassima Kemache in Industrial & engineering chemistry research, Vol. 49 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 3 (Fevrier 2010) . - pp. 971–979 Titre : Activity and selectivity of nanostructured sulfur-doped Pd/SBA-15 catalyst for vegetable oil hardening Type de document : texte imprimé Auteurs : Nassima Kemache, Auteur ; Safia Hamoudi, Auteur ; Joseph Arul, Auteur Année de publication : 2010 Article en page(s) : pp. 971–979 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Activity--Selectivity--Sulfur--Nanostructured--Catalyst--Pd/SBA-15--Doped--Vegetable--Oil--Hardening Résumé : Sunflower and canola oils were hardened over a novel sulfur-promoted Pd catalyst. The formulated catalyst comprised of 0.7 wt % palladium nanoparticles promoted with 0.3 wt % sulfur highly dispersed on mesoporous silica SBA-15 (0.7% Pd−0.3% S/SBA-15). 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. Under similar temperature and H2-pressure conditions, sunflower and canola oils exhibited different reactivities toward hydrogenation. For both oils, the activity of the catalyst increased with the temperature and with the pressure. However, increasing the temperature raised the levels of trans C18:1 especially at low hydrogen pressure. Partial hydrogenation of both oils from initial iodine (IVo) values of 120−130 to a final value of 90 with the sulfur-doped Pd catalyst yielded modified oils with a low TFA level (6%) and also controlled the formation of SFA (7%) under mild temperature conditions (80 °C) and relatively moderate hydrogen pressure (9 atm). The sulfur-doped Pd catalyst proved to be versatile and more active than the Pd catalyst using similar Pd loading and reaction conditions but slightly less selective toward monoene formation. It was found that the intraparticle diffusion limitation for triglycerides does not occur during the hydrogenation of vegetable oils, but the hydrogen transfer limitation cannot be neglected and could partially explain the formation of trans-fatty acids. Modulating the Weisz−Prater modulus used to demonstrate the presence of H2 intraparticle gradients could be a criterion to control the hydrogenation and cis−trans isomerization activities. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9006529 [article] Activity and selectivity of nanostructured sulfur-doped Pd/SBA-15 catalyst for vegetable oil hardening [texte imprimé] / Nassima Kemache, Auteur ; Safia Hamoudi, Auteur ; Joseph Arul, Auteur . - 2010 . - pp. 971–979. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 3 (Fevrier 2010) . - pp. 971–979 Mots-clés : Activity--Selectivity--Sulfur--Nanostructured--Catalyst--Pd/SBA-15--Doped--Vegetable--Oil--Hardening Résumé : Sunflower and canola oils were hardened over a novel sulfur-promoted Pd catalyst. The formulated catalyst comprised of 0.7 wt % palladium nanoparticles promoted with 0.3 wt % sulfur highly dispersed on mesoporous silica SBA-15 (0.7% Pd−0.3% S/SBA-15). 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. Under similar temperature and H2-pressure conditions, sunflower and canola oils exhibited different reactivities toward hydrogenation. For both oils, the activity of the catalyst increased with the temperature and with the pressure. However, increasing the temperature raised the levels of trans C18:1 especially at low hydrogen pressure. Partial hydrogenation of both oils from initial iodine (IVo) values of 120−130 to a final value of 90 with the sulfur-doped Pd catalyst yielded modified oils with a low TFA level (6%) and also controlled the formation of SFA (7%) under mild temperature conditions (80 °C) and relatively moderate hydrogen pressure (9 atm). The sulfur-doped Pd catalyst proved to be versatile and more active than the Pd catalyst using similar Pd loading and reaction conditions but slightly less selective toward monoene formation. It was found that the intraparticle diffusion limitation for triglycerides does not occur during the hydrogenation of vegetable oils, but the hydrogen transfer limitation cannot be neglected and could partially explain the formation of trans-fatty acids. Modulating the Weisz−Prater modulus used to demonstrate the presence of H2 intraparticle gradients could be a criterion to control the hydrogenation and cis−trans isomerization activities. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9006529

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