Documents disponibles écrits par cet auteur

Deliquescence in the hydrolysis of sodium borohydride by water vapor / Amy M. Beaird in Industrial & engineering chemistry research, Vol. 49 N° 20 (Octobre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 20 (Octobre 2010) . - pp. 9596–9599 Titre : Deliquescence in the hydrolysis of sodium borohydride by water vapor Type de document : texte imprimé Auteurs : Amy M. Beaird, Auteur ; Thomas A. Davis, Auteur ; Michael A. Matthews, Auteur Année de publication : 2011 Article en page(s) : pp. 9596–9599 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydrolysis  Water  Vapor Résumé : The interaction between sodium borohydride (NaBH4) and water vapor leading to hydrolysis and hydrogen generation has been investigated by a visual technique. In situ video monitoring confirms that reaction is preceded by deliquescence of NaBH4 upon exposure to water vapor, forming a viscous liquid solution that releases hydrogen. A regime of temperature and relative humidity under which the deliquescence is favorable has been determined. A relative humidity threshold exists below which NaBH4 powder does not absorb water vapor into the bulk to form a solution and thereby does not undergo reaction to form hydrogen. The deliquescence behavior of NaBH4 in water vapor provides an alternative reaction pathway that has potential to improve hydrogen storage density by reducing excess water and other additives. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100244v [article] Deliquescence in the hydrolysis of sodium borohydride by water vapor [texte imprimé] / Amy M. Beaird, Auteur ; Thomas A. Davis, Auteur ; Michael A. Matthews, Auteur . - 2011 . - pp. 9596–9599. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 20 (Octobre 2010) . - pp. 9596–9599 Mots-clés : Hydrolysis  Water  Vapor Résumé : The interaction between sodium borohydride (NaBH4) and water vapor leading to hydrolysis and hydrogen generation has been investigated by a visual technique. In situ video monitoring confirms that reaction is preceded by deliquescence of NaBH4 upon exposure to water vapor, forming a viscous liquid solution that releases hydrogen. A regime of temperature and relative humidity under which the deliquescence is favorable has been determined. A relative humidity threshold exists below which NaBH4 powder does not absorb water vapor into the bulk to form a solution and thereby does not undergo reaction to form hydrogen. The deliquescence behavior of NaBH4 in water vapor provides an alternative reaction pathway that has potential to improve hydrogen storage density by reducing excess water and other additives. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100244v

Hydrogen generation from chemical hydrides / Eyma Y. Marrero-Alfonso in Industrial & engineering chemistry research, Vol. 48 N° 8 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3703–3712 Titre : Hydrogen generation from chemical hydrides Type de document : texte imprimé Auteurs : Eyma Y. Marrero-Alfonso, Auteur ; Amy M. Beaird, Auteur ; Thomas A. Davis, Auteur Année de publication : 2009 Article en page(s) : pp. 3703–3712 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Chemical  hydrides  Hydrogen  Hydrolysis Résumé : Complex chemical hydrides can be used to store and deliver hydrogen gas to fuel cells, and thus are one of several candidate materials to be used in storage systems for the hydrogen economy. These hydrides have high native hydrogen content, and hydrogen can be released via several chemical pathways. This review summarizes the extensive literature on the kinetic and thermodynamic properties of the various reactions of chemical hydrides, with an emphasis on hydrolysis. These properties are significant because they affect all aspects of system design, as well as the recovery and recycle of the byproducts. Hydrolysis of chemical hydrides takes place at relatively low temperatures and gives promising theoretical hydrogen storage efficiencies. Complications include metastable kinetic pathways as well as inefficient utilization of water in the byproducts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016225 [article] Hydrogen generation from chemical hydrides [texte imprimé] / Eyma Y. Marrero-Alfonso, Auteur ; Amy M. Beaird, Auteur ; Thomas A. Davis, Auteur . - 2009 . - pp. 3703–3712. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 3703–3712 Mots-clés : Chemical  hydrides  Hydrogen  Hydrolysis Résumé : Complex chemical hydrides can be used to store and deliver hydrogen gas to fuel cells, and thus are one of several candidate materials to be used in storage systems for the hydrogen economy. These hydrides have high native hydrogen content, and hydrogen can be released via several chemical pathways. This review summarizes the extensive literature on the kinetic and thermodynamic properties of the various reactions of chemical hydrides, with an emphasis on hydrolysis. These properties are significant because they affect all aspects of system design, as well as the recovery and recycle of the byproducts. Hydrolysis of chemical hydrides takes place at relatively low temperatures and gives promising theoretical hydrogen storage efficiencies. Complications include metastable kinetic pathways as well as inefficient utilization of water in the byproducts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8016225

Thermal dehydration and vibrational spectra of hydrated sodium metaborates / Amy M. Beaird in Industrial & engineering chemistry research, Vol. 50 N° 13 (Juillet 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 13 (Juillet 2011) . - pp. 7746–7752 Titre : Thermal dehydration and vibrational spectra of hydrated sodium metaborates Type de document : texte imprimé Auteurs : Amy M. Beaird, Auteur ; Li Peng, Auteur ; Hilary S. Marsh, Auteur Année de publication : 2011 Article en page(s) : pp. 7746–7752 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalysis  Reaction  kinetics  Inorganic  reaction  mechanisms Résumé : Sodium metaborate hydrates are a class of compounds represented by the stoichiometry NaBO2·xH2O. Recently, sodium metaborate has received attention as the byproduct of sodium borohydride hydrolysis, a reaction that is under consideration for hydrogen storage applications. The aim of this work was to understand the disposition of water in the crystal structure of hydrated sodium metaborates and to characterize the thermal stability and dehydration of the various hydrated species to optimize hydrogen storage efficiency as well as recyclability of the borate. Observations from a suite of analytical techniques including thermal analyses (thermogravimetric analysis/differential scanning calorimetry), X-ray diffraction, and Raman spectroscopy were correlated to characterize the dehydration mechanism of commercially available sodium metaborates, with an emphasis on the dihydrate (x = 2). A transformation from tetrahedrally coordinated boron to trigonal boron occurs when NaB(OH)4 (x = 2) is heated between 25 and 400 °C. The first dehydration to Na3[B3O5(OH)2] (x = 1/3) releases 5 mol of water between 83 and 155 °C. The final mole of water is released between 249 and 280 °C, and Na3B3O6 (x = 0) is formed. Raman spectra are reported for x = 2 and 1/3 for the first time. First-principles density functional theory was used to compute Raman spectra of the x = 1/3 and 2 material in order to assign the modes. We found reasonably good agreement between the experimentally measured and calculated vibrational frequencies. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102345j [article] Thermal dehydration and vibrational spectra of hydrated sodium metaborates [texte imprimé] / Amy M. Beaird, Auteur ; Li Peng, Auteur ; Hilary S. Marsh, Auteur . - 2011 . - pp. 7746–7752. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 13 (Juillet 2011) . - pp. 7746–7752 Mots-clés : Catalysis  Reaction  kinetics  Inorganic  reaction  mechanisms Résumé : Sodium metaborate hydrates are a class of compounds represented by the stoichiometry NaBO2·xH2O. Recently, sodium metaborate has received attention as the byproduct of sodium borohydride hydrolysis, a reaction that is under consideration for hydrogen storage applications. The aim of this work was to understand the disposition of water in the crystal structure of hydrated sodium metaborates and to characterize the thermal stability and dehydration of the various hydrated species to optimize hydrogen storage efficiency as well as recyclability of the borate. Observations from a suite of analytical techniques including thermal analyses (thermogravimetric analysis/differential scanning calorimetry), X-ray diffraction, and Raman spectroscopy were correlated to characterize the dehydration mechanism of commercially available sodium metaborates, with an emphasis on the dihydrate (x = 2). A transformation from tetrahedrally coordinated boron to trigonal boron occurs when NaB(OH)4 (x = 2) is heated between 25 and 400 °C. The first dehydration to Na3[B3O5(OH)2] (x = 1/3) releases 5 mol of water between 83 and 155 °C. The final mole of water is released between 249 and 280 °C, and Na3B3O6 (x = 0) is formed. Raman spectra are reported for x = 2 and 1/3 for the first time. First-principles density functional theory was used to compute Raman spectra of the x = 1/3 and 2 material in order to assign the modes. We found reasonably good agreement between the experimentally measured and calculated vibrational frequencies. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie102345j