Documents disponibles écrits par cet auteur

Influence of the activation conditions on the porosity development of herringbone carbon nanofibers / Vicente Jiménez in Chemical engineering journal, Vol. 155 N° 3 (Decembre 2009) 

Public ISBD [article]  in Chemical engineering journal > Vol. 155 N° 3 (Decembre 2009) . - pp. 931-940 Titre : Influence of the activation conditions on the porosity development of herringbone carbon nanofibers Type de document : texte imprimé Auteurs : Vicente Jiménez, Auteur ; José Antonio Díaz, Auteur ; Paula Sánchez, Auteur Année de publication : 2010 Article en page(s) : pp. 931-940 Note générale : Génie Chimique Langues : Anglais (eng) Mots-clés : Carbon  nanofibers  Activation  Porosity  Carbon  yield  Adsorption Index. décimale : 660 Résumé : The influence of different activation conditions, including activating agent/CNFs mass ratio, activation temperature, activation time and He flow rate, on the pore structure development of herringbone carbon nanofibers (CNFs) has been studied. Activation conditions with a KOH/CNFs mass ratio = 5/1, activation temperature = 850 °C, activation time = 3 h and He flow rate = 700 mL min−1 gave rise to a material with a very high micropore volume, a quite narrow micropore distribution and the highest surface area (increased by a factor of 4.5 in comparison to the raw CNFs). The conditions outlined above also led to the creation of some mesopores in the activation process due to the strong interaction between the CNFs and the activating agent. On the other hand, the use of other activation conditions led to activated CNFs with different structural properties. For example, activated CNFs with the lowest mesopore volume were obtained when the activation conditions were KOH/CNFs mass ratio = 5/1, activation temperature = 900 °C, activation time = 3 h and He flow rate = 500 mL min−1. Therefore, depending on the final application of the activated CNFs, it is possible to control their pore structure by selecting appropriate activation conditions. DEWEY : 660 ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFJ-4X9NVBP-C&_user=6 [...] [article] Influence of the activation conditions on the porosity development of herringbone carbon nanofibers [texte imprimé] / Vicente Jiménez, Auteur ; José Antonio Díaz, Auteur ; Paula Sánchez, Auteur . - 2010 . - pp. 931-940. Génie Chimique Langues : Anglais (eng) in Chemical engineering journal > Vol. 155 N° 3 (Decembre 2009) . - pp. 931-940 Mots-clés : Carbon  nanofibers  Activation  Porosity  Carbon  yield  Adsorption Index. décimale : 660 Résumé : The influence of different activation conditions, including activating agent/CNFs mass ratio, activation temperature, activation time and He flow rate, on the pore structure development of herringbone carbon nanofibers (CNFs) has been studied. Activation conditions with a KOH/CNFs mass ratio = 5/1, activation temperature = 850 °C, activation time = 3 h and He flow rate = 700 mL min−1 gave rise to a material with a very high micropore volume, a quite narrow micropore distribution and the highest surface area (increased by a factor of 4.5 in comparison to the raw CNFs). The conditions outlined above also led to the creation of some mesopores in the activation process due to the strong interaction between the CNFs and the activating agent. On the other hand, the use of other activation conditions led to activated CNFs with different structural properties. For example, activated CNFs with the lowest mesopore volume were obtained when the activation conditions were KOH/CNFs mass ratio = 5/1, activation temperature = 900 °C, activation time = 3 h and He flow rate = 500 mL min−1. Therefore, depending on the final application of the activated CNFs, it is possible to control their pore structure by selecting appropriate activation conditions. DEWEY : 660 ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFJ-4X9NVBP-C&_user=6 [...]

Pilot plant scale study of the influence of the operating conditions in the production of carbon nanofibers / Vicente Jiménez in Industrial & engineering chemistry research, Vol. 48 N° 18 (Septembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8407–8417 Titre : Pilot plant scale study of the influence of the operating conditions in the production of carbon nanofibers Type de document : texte imprimé Auteurs : Vicente Jiménez, Auteur ; Antonio Nieto-Márquez, Auteur ; José Antonio Díaz, Auteur Année de publication : 2010 Article en page(s) : pp. 8407–8417 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon  nanofibers  Pilot  scale  Fixed-bed  reactor Résumé : In this paper, the optimization of typical reaction variables for a pilot scale synthesis of carbon nanofibers (CNFs) using a fixed-bed reactor has been carried out to provide a more economically viable large scale production of these materials. Using a Ni/SiO2 catalyst (10 wt % Ni) and ethylene as the carbon source, the optimum value of temperature, space velocity, and H2/C2H4 ratio (v/v) in terms of carbon yield was 600 °C, 10000 h−1, and 1:4, respectively. The modification of these variables caused a significant change in the type and amount of solid carbon recovered. Carbon product characterization demonstrated that CNFs with mesoporous character, large external surface, and good thermal stability and crystallinity were obtained. Finally, results demonstrated a successful scale-up by a factor of 45 in the pilot plant scale; a CNFs yield of 106 gCNFs/gcatalytic metal could be obtained at optimal conditions during a reaction time of 60 min at optimal conditions in the pilot plant scale. For the same reaction conditions, only 80 gCNFs/gcatalytic metal were obtained in the laboratory reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005386 [article] Pilot plant scale study of the influence of the operating conditions in the production of carbon nanofibers [texte imprimé] / Vicente Jiménez, Auteur ; Antonio Nieto-Márquez, Auteur ; José Antonio Díaz, Auteur . - 2010 . - pp. 8407–8417. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 18 (Septembre 2009) . - pp. 8407–8417 Mots-clés : Carbon  nanofibers  Pilot  scale  Fixed-bed  reactor Résumé : In this paper, the optimization of typical reaction variables for a pilot scale synthesis of carbon nanofibers (CNFs) using a fixed-bed reactor has been carried out to provide a more economically viable large scale production of these materials. Using a Ni/SiO2 catalyst (10 wt % Ni) and ethylene as the carbon source, the optimum value of temperature, space velocity, and H2/C2H4 ratio (v/v) in terms of carbon yield was 600 °C, 10000 h−1, and 1:4, respectively. The modification of these variables caused a significant change in the type and amount of solid carbon recovered. Carbon product characterization demonstrated that CNFs with mesoporous character, large external surface, and good thermal stability and crystallinity were obtained. Finally, results demonstrated a successful scale-up by a factor of 45 in the pilot plant scale; a CNFs yield of 106 gCNFs/gcatalytic metal could be obtained at optimal conditions during a reaction time of 60 min at optimal conditions in the pilot plant scale. For the same reaction conditions, only 80 gCNFs/gcatalytic metal were obtained in the laboratory reactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9005386

Pilot plant scale synthesis of CNS / Vicente Jiménez in Industrial & engineering chemistry research, Vol. 51 N° 19 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 19 (Mai 2012) . - pp. 6745-6752 Titre : Pilot plant scale synthesis of CNS : Influence of the operating conditions Type de document : texte imprimé Auteurs : Vicente Jiménez, Auteur ; Alfredo Muñoz, Auteur ; Paula Sánchez, Auteur Année de publication : 2012 Article en page(s) : pp. 6745-6752 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Operating  conditions  Pilot  plant  scale Résumé : The present work was an in-depth study related to synthesis of carbon nanospheres (CNSs) at different scales (lab and pilot) with the end goal to economize the production of these materials on a large scale. Synthesis of large amounts of CNSs relies on the careful control of the operating conditions such as space velocity (helium flow rate), hydsocarbon (benzene) content in feed stream, and synthesis time. The alteration of these variables caused important changes in both the yield and properties of the obtained materials. In general, characterization results of the synthesized CNSs demonstrated that they showed low BET surface area and pore volume values typical of spherical geometrical bodies, good thermal stability, and good crystallinity. Normally, CNSs are presented as conglomerates as consequence of the accretion via the carbon atoms at the edge of the "curling" graphitic flakes. Finally, results demonstrated a successful scale up, obtaining a CNSs yield at pilot scale considerably superior (factor of 3.9) to that obtained at laboratory scale. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25900229 [article] Pilot plant scale synthesis of CNS : Influence of the operating conditions [texte imprimé] / Vicente Jiménez, Auteur ; Alfredo Muñoz, Auteur ; Paula Sánchez, Auteur . - 2012 . - pp. 6745-6752. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 19 (Mai 2012) . - pp. 6745-6752 Mots-clés : Operating  conditions  Pilot  plant  scale Résumé : The present work was an in-depth study related to synthesis of carbon nanospheres (CNSs) at different scales (lab and pilot) with the end goal to economize the production of these materials on a large scale. Synthesis of large amounts of CNSs relies on the careful control of the operating conditions such as space velocity (helium flow rate), hydsocarbon (benzene) content in feed stream, and synthesis time. The alteration of these variables caused important changes in both the yield and properties of the obtained materials. In general, characterization results of the synthesized CNSs demonstrated that they showed low BET surface area and pore volume values typical of spherical geometrical bodies, good thermal stability, and good crystallinity. Normally, CNSs are presented as conglomerates as consequence of the accretion via the carbon atoms at the edge of the "curling" graphitic flakes. Finally, results demonstrated a successful scale up, obtaining a CNSs yield at pilot scale considerably superior (factor of 3.9) to that obtained at laboratory scale. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25900229