Documents disponibles écrits par cet auteur

An updated review of synthesis parameters and growth mechanisms for carbon nanotubes in fluidized beds / Kieran J. MacKenzie in Industrial & engineering chemistry research, Vol. 49 N° 11 (Juin 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 11 (Juin 2010) . - pp. 5323–5338 Titre : An updated review of synthesis parameters and growth mechanisms for carbon nanotubes in fluidized beds Type de document : texte imprimé Auteurs : Kieran J. MacKenzie, Auteur ; Oscar M. Dunens, Auteur ; Andrew T. Harris, Auteur Année de publication : 2010 Article en page(s) : pp. 5323–5338 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Carbon  Nanotubes Résumé : Research published since 2006 on the synthesis of carbon nanotubes (CNTs) using chemical vapor deposition (CVD) in a fluidized bed reactor is reviewed. A complete account of experimental procedures, including upstream treatments (catalyst preparation, calcination, and reduction), synthesis conditions, and downstream processes (purification) is presented in an attempt to determine the effect of these variables on carbon nanotube morphology, diameter, yield, and quality. The formation and growth mechanisms of carbon nanotubes by CVD is reviewed in detail in an attempt to account for discrepancies in the properties of CNTs produced from experiments at superficially similar conditions. This reveals that the underlying variables that appear to control growth are not directly manipulated in the CVD process; rather they are determined by complex interactions between variables. Thus, the current “change-one-factor-at-a-time” experimental paradigm, which assumes orthogonal variables, is the most likely source of the conflicting experimental results reported in the literature, and does not give insight into CNT growth or permit “global” process optimization. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9019787 [article] An updated review of synthesis parameters and growth mechanisms for carbon nanotubes in fluidized beds [texte imprimé] / Kieran J. MacKenzie, Auteur ; Oscar M. Dunens, Auteur ; Andrew T. Harris, Auteur . - 2010 . - pp. 5323–5338. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 11 (Juin 2010) . - pp. 5323–5338 Mots-clés : Carbon  Nanotubes Résumé : Research published since 2006 on the synthesis of carbon nanotubes (CNTs) using chemical vapor deposition (CVD) in a fluidized bed reactor is reviewed. A complete account of experimental procedures, including upstream treatments (catalyst preparation, calcination, and reduction), synthesis conditions, and downstream processes (purification) is presented in an attempt to determine the effect of these variables on carbon nanotube morphology, diameter, yield, and quality. The formation and growth mechanisms of carbon nanotubes by CVD is reviewed in detail in an attempt to account for discrepancies in the properties of CNTs produced from experiments at superficially similar conditions. This reveals that the underlying variables that appear to control growth are not directly manipulated in the CVD process; rather they are determined by complex interactions between variables. Thus, the current “change-one-factor-at-a-time” experimental paradigm, which assumes orthogonal variables, is the most likely source of the conflicting experimental results reported in the literature, and does not give insight into CNT growth or permit “global” process optimization. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9019787

Large-Scale Synthesis of Double-Walled Carbon Nanotubes in Fluidized Beds / Oscar M. Dunens in Industrial & engineering chemistry research, Vol. 49 N° 9 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4031–4035 Titre : Large-Scale Synthesis of Double-Walled Carbon Nanotubes in Fluidized Beds Type de document : texte imprimé Auteurs : Oscar M. Dunens, Auteur ; Kieran J. MacKenzie, Auteur ; Andrew T. Harris, Auteur Année de publication : 2010 Article en page(s) : pp. 4031–4035 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Carbon  Nanotubes Résumé : Double-walled carbon nanotubes (DWCNTs) are a unique allotrope of carbon with numerous potential applications including use in electronic and nanomechanical devices. However, existing methods and reaction conditions for DWCNT synthesis are inherently unscaleable, and production is limited to gram per hour quantities. Here, we report the synthesis of well-graphitized DWCNTs using fluidized bed chemical vapor deposition on an alumina-supported iron−molybdenum catalyst. Reaction products were analyzed using thermogravimetric analysis, Raman spectroscopy, and scanning and transmission electron microscopies. At a synthesis temperature of 850 °C and with use of methane as the carbon source, a 278% carbon yield relative to the weight of the metal catalyst was obtained. Carbon products consisted of approximately 75% DWCNTs with a good degree of wall graphitization (IG/ID = 4.85). The production technique and reaction conditions described here are capable of being applied at industrial scale. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100059q [article] Large-Scale Synthesis of Double-Walled Carbon Nanotubes in Fluidized Beds [texte imprimé] / Oscar M. Dunens, Auteur ; Kieran J. MacKenzie, Auteur ; Andrew T. Harris, Auteur . - 2010 . - pp. 4031–4035. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4031–4035 Mots-clés : Carbon  Nanotubes Résumé : Double-walled carbon nanotubes (DWCNTs) are a unique allotrope of carbon with numerous potential applications including use in electronic and nanomechanical devices. However, existing methods and reaction conditions for DWCNT synthesis are inherently unscaleable, and production is limited to gram per hour quantities. Here, we report the synthesis of well-graphitized DWCNTs using fluidized bed chemical vapor deposition on an alumina-supported iron−molybdenum catalyst. Reaction products were analyzed using thermogravimetric analysis, Raman spectroscopy, and scanning and transmission electron microscopies. At a synthesis temperature of 850 °C and with use of methane as the carbon source, a 278% carbon yield relative to the weight of the metal catalyst was obtained. Carbon products consisted of approximately 75% DWCNTs with a good degree of wall graphitization (IG/ID = 4.85). The production technique and reaction conditions described here are capable of being applied at industrial scale. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100059q

Process parameter interaction effects during carbon nanotube synthesis in fluidized beds / Chee Howe See in Industrial & engineering chemistry research, Vol. 47 N°20 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7686-7692 Titre : Process parameter interaction effects during carbon nanotube synthesis in fluidized beds Type de document : texte imprimé Auteurs : Chee Howe See, Editeur scientifique ; Oscar M. Dunens, Editeur scientifique ; Kieran J. MacKenzie, Editeur scientifique Année de publication : 2008 Article en page(s) : P. 7686-7692 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon  nanotube  (CNT) Résumé : The interaction effects between temperature, catalyst properties, fluidization conditions, and deposition time during carbon nanotube (CNT) synthesis by chemical vapor deposition in a fluidized bed were investigated. While numerous investigations have attempted to correlate process parameters with CNT characteristics, selectivity and yield, the interaction between process parameters is often ignored. Parametric interactions in this process have been investigated using a factorial design methodology. Besides the main effects of synthesis temperature, deposition time, and catalyst type, the interaction parameters temperature−time and temperature−catalyst were found to significantly influence the resultant carbon and CNT yields. These results lay the foundation for a detailed parametric analysis toward the optimization of CNT synthesis in fluidized beds, which takes into account these interaction effects. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701786p [article] Process parameter interaction effects during carbon nanotube synthesis in fluidized beds [texte imprimé] / Chee Howe See, Editeur scientifique ; Oscar M. Dunens, Editeur scientifique ; Kieran J. MacKenzie, Editeur scientifique . - 2008 . - P. 7686-7692. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7686-7692 Mots-clés : Carbon  nanotube  (CNT) Résumé : The interaction effects between temperature, catalyst properties, fluidization conditions, and deposition time during carbon nanotube (CNT) synthesis by chemical vapor deposition in a fluidized bed were investigated. While numerous investigations have attempted to correlate process parameters with CNT characteristics, selectivity and yield, the interaction between process parameters is often ignored. Parametric interactions in this process have been investigated using a factorial design methodology. Besides the main effects of synthesis temperature, deposition time, and catalyst type, the interaction parameters temperature−time and temperature−catalyst were found to significantly influence the resultant carbon and CNT yields. These results lay the foundation for a detailed parametric analysis toward the optimization of CNT synthesis in fluidized beds, which takes into account these interaction effects. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701786p