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

Biogenic Synthesis of Au Nanoparticles Using Vascular Plants / Roza Bali in Industrial & engineering chemistry research, Vol. 49 N° 24 (Décembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12762–12772 Titre : Biogenic Synthesis of Au Nanoparticles Using Vascular Plants Type de document : texte imprimé Auteurs : Roza Bali, Auteur ; Andrew T. Harris, Auteur Année de publication : 2011 Article en page(s) : pp. 12762–12772 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Nanoparticles  Biogenic Résumé : The known metallophytes Brassica juncea (B. juncea) and Medicago sativa (M. sativa) were investigated for their ability to accumulate and sequester gold (Au) from aqueous solutions of KAuCl4. Once sequestered, some of the metal was stored as nanoparticles, throughout the epidermis, cortex, and vascular tissue for both species, but predominantly located in the xylem parenchyma cells. Nanoparticle size distribution within the plant tissues was determined. In general, particle sizes ranged between 2 nm to 2 μm in B. juncea and 2 nm to 1 μm in M. sativa and was location dependent; root located nanoparticles had similar size distributions in both species, whereas the distribution within above ground tissues differed between M. sativa and B. juncea, with B. juncea showing a much broader range of particle sizes. Au(0) nanoparticles were also formed ex vivo following contact between root exudates and an aqueous solution of KAuCl4 resulting in the reduction of Au(III) to Au(0). The largest proportion of particles was in the range 5−10 nm (B. juncea) and 10−20 nm (M. sativa). The mechanism of growth of Au(0) nanoparticles using live plants, both in vivo and ex vivo is consistent with Turkevich [Gold Bull. 1985, 18 (3), 86−91], who suggested that the process of Au(0) particle formation involved the interplay of crystal nucleation, growth, and coagulation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101600m [article] Biogenic Synthesis of Au Nanoparticles Using Vascular Plants [texte imprimé] / Roza Bali, Auteur ; Andrew T. Harris, Auteur . - 2011 . - pp. 12762–12772. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12762–12772 Mots-clés : Nanoparticles  Biogenic Résumé : The known metallophytes Brassica juncea (B. juncea) and Medicago sativa (M. sativa) were investigated for their ability to accumulate and sequester gold (Au) from aqueous solutions of KAuCl4. Once sequestered, some of the metal was stored as nanoparticles, throughout the epidermis, cortex, and vascular tissue for both species, but predominantly located in the xylem parenchyma cells. Nanoparticle size distribution within the plant tissues was determined. In general, particle sizes ranged between 2 nm to 2 μm in B. juncea and 2 nm to 1 μm in M. sativa and was location dependent; root located nanoparticles had similar size distributions in both species, whereas the distribution within above ground tissues differed between M. sativa and B. juncea, with B. juncea showing a much broader range of particle sizes. Au(0) nanoparticles were also formed ex vivo following contact between root exudates and an aqueous solution of KAuCl4 resulting in the reduction of Au(III) to Au(0). The largest proportion of particles was in the range 5−10 nm (B. juncea) and 10−20 nm (M. sativa). The mechanism of growth of Au(0) nanoparticles using live plants, both in vivo and ex vivo is consistent with Turkevich [Gold Bull. 1985, 18 (3), 86−91], who suggested that the process of Au(0) particle formation involved the interplay of crystal nucleation, growth, and coagulation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101600m

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

Review of major design and scale-up considerations for solar photocatalytic reactors / Rowan J. Braham in Industrial & engineering chemistry research, Vol. 48 N° 19 (Octobre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8890–8905 Titre : Review of major design and scale-up considerations for solar photocatalytic reactors Type de document : texte imprimé Auteurs : Rowan J. Braham, Auteur ; Andrew T. Harris, Auteur Année de publication : 2009 Article en page(s) : pp. 8890–8905 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Photocatalytic  reactors  Industrial-scale  implementation Résumé : Photocatalytic processes are applicable in wastewater treatment, energy production, chemical synthesis, and greenhouse gas mitigation and thus have the potential to address both the consumption of nonrenewable fossil fuels and global warming, two of the greatest problems facing humankind. The ability to achieve these outcomes using only solar energy as an input is particularly attractive. However, the implementation of most photocatalytic processes at an effective scale requires the use of a photoreactor, a device which brings photons, a photocatalyst and reactants into contact, as well as collecting the reaction products. In this work, we review the state-of-the-art in solar photoreactor design and assess those systems which are most applicable for industrial-scale implementation. Designs for parabolic trough, compound parabolic, inclined plate, double skin sheet, rotating disk, water bell, fiber optic, and fixed/fluidized bed photoreactors are qualitatively discussed and compared. Compound parabolic photoreactors are most suited to near term applications at pilot-scale (>1000 L/day) due to their advantageous light collecting properties and well-known design methodology. Double-skin sheet photoreactors are also suited to near term applications; however, significantly less is known about their design and performance discrepancies between studies in the literature have been reported. Compared to other photoreactor designs, the significantly simplified design and low material cost of inclined plate photoreactors makes them particularly suitable for use in economically and logistically challenged areas where the volumes to be treated are small (<100 L/day). Fluidized bed photoreactors are highly efficient, but more research is needed into their design and operation for effective use with solar radiation. The other photoreactor designs reviewed are unlikely to see wide use due to, variously, high mechanical complexity, poor efficiency, and/or susceptibility to environmental conditions but may find limited use in specialized applications, e.g. in instances where it is advantageous to separate the light gathering and photocatalytic components of the photoreactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900859z [article] Review of major design and scale-up considerations for solar photocatalytic reactors [texte imprimé] / Rowan J. Braham, Auteur ; Andrew T. Harris, Auteur . - 2009 . - pp. 8890–8905. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8890–8905 Mots-clés : Photocatalytic  reactors  Industrial-scale  implementation Résumé : Photocatalytic processes are applicable in wastewater treatment, energy production, chemical synthesis, and greenhouse gas mitigation and thus have the potential to address both the consumption of nonrenewable fossil fuels and global warming, two of the greatest problems facing humankind. The ability to achieve these outcomes using only solar energy as an input is particularly attractive. However, the implementation of most photocatalytic processes at an effective scale requires the use of a photoreactor, a device which brings photons, a photocatalyst and reactants into contact, as well as collecting the reaction products. In this work, we review the state-of-the-art in solar photoreactor design and assess those systems which are most applicable for industrial-scale implementation. Designs for parabolic trough, compound parabolic, inclined plate, double skin sheet, rotating disk, water bell, fiber optic, and fixed/fluidized bed photoreactors are qualitatively discussed and compared. Compound parabolic photoreactors are most suited to near term applications at pilot-scale (>1000 L/day) due to their advantageous light collecting properties and well-known design methodology. Double-skin sheet photoreactors are also suited to near term applications; however, significantly less is known about their design and performance discrepancies between studies in the literature have been reported. Compared to other photoreactor designs, the significantly simplified design and low material cost of inclined plate photoreactors makes them particularly suitable for use in economically and logistically challenged areas where the volumes to be treated are small (<100 L/day). Fluidized bed photoreactors are highly efficient, but more research is needed into their design and operation for effective use with solar radiation. The other photoreactor designs reviewed are unlikely to see wide use due to, variously, high mechanical complexity, poor efficiency, and/or susceptibility to environmental conditions but may find limited use in specialized applications, e.g. in instances where it is advantageous to separate the light gathering and photocatalytic components of the photoreactor. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900859z