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