Documents disponibles écrits par cet auteur

Perspective for extended group-contribution methods for the prediction of activity coefficients accounting for sterical effects. Linking UNIFAC and the group vector space method / Stephan Machefer ; Martin Grasemann ; Klaus Schnitzlein in Industrial & engineering chemistry research, Vol. 47 n°24 (Décembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10080–10085 Titre : Perspective for extended group-contribution methods for the prediction of activity coefficients accounting for sterical effects. Linking UNIFAC and the group vector space method Type de document : texte imprimé Auteurs : Stephan Machefer, Auteur ; Martin Grasemann, Auteur ; Klaus Schnitzlein, Auteur Année de publication : 2009 Article en page(s) : p. 10080–10085 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Vector  space  Wen,  X.  Qiang,  Y. Résumé : Group contribution methods for the calculation of an activity coefficient such as UNIFAC (universal factorial activity coefficient) currently do not take into account sterical effects. Consequently one of the major deficiencies of such methods is their inability to resolve isomeric systems and their often insufficient accuracy for systems including molecules of very different size. In this paper an approach is presented by which sterical information can be implemented into those methods by means of a modified group vector space (GVS) procedure. (Wen, X.; Qiang, Y. Group Vector Space method for estimating melting and boiling points of organic compounds. Ind. Eng. Chem. Res. 2002, 41, 5534−5537.) Exemplary calculations with UNIFAC/GVS underline the potential of this new approach resulting in a perspective for substantially improved group contributions methods with a wider range of applicability and even more reliable predictive performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800980m [article] Perspective for extended group-contribution methods for the prediction of activity coefficients accounting for sterical effects. Linking UNIFAC and the group vector space method [texte imprimé] / Stephan Machefer, Auteur ; Martin Grasemann, Auteur ; Klaus Schnitzlein, Auteur . - 2009 . - p. 10080–10085. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°24 (Décembre 2008) . - p. 10080–10085 Mots-clés : Vector  space  Wen,  X.  Qiang,  Y. Résumé : Group contribution methods for the calculation of an activity coefficient such as UNIFAC (universal factorial activity coefficient) currently do not take into account sterical effects. Consequently one of the major deficiencies of such methods is their inability to resolve isomeric systems and their often insufficient accuracy for systems including molecules of very different size. In this paper an approach is presented by which sterical information can be implemented into those methods by means of a modified group vector space (GVS) procedure. (Wen, X.; Qiang, Y. Group Vector Space method for estimating melting and boiling points of organic compounds. Ind. Eng. Chem. Res. 2002, 41, 5534−5537.) Exemplary calculations with UNIFAC/GVS underline the potential of this new approach resulting in a perspective for substantially improved group contributions methods with a wider range of applicability and even more reliable predictive performance. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800980m

Three-phase catalytic hydrogenation of a functionalized alkyne / Andrea Bruehwiler in Industrial & engineering chemistry research, Vol. 47 N°18 (Septembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°18 (Septembre 2008) . - p. 6862–6869 Titre : Three-phase catalytic hydrogenation of a functionalized alkyne : mass transfer and kinetic studies with in situ hydrogen monitoring Type de document : texte imprimé Auteurs : Andrea Bruehwiler, Auteur ; Natalia Semagina, Auteur ; Martin Grasemann, Auteur Année de publication : 2008 Article en page(s) : p. 6862–6869 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Mass  transfer  interactions  Hydrogen  Catalytic  hydrogenation Résumé : Systematic studies of mass transfer interactions with intrinsic reaction kinetics were performed for the three-phase selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE) over a modified Pd/CaCO3 catalyst under solvent free conditions. Hydrogen concentration in the liquid phase (CH2,b) was monitored in situ during the catalytic reaction by means of the “Fugatron” analyzer. Reactions were carried out in an autoclave at different stirring rates at two concentrations of hydrogen (5 and 13 mol·m−3). For stirring speeds higher than 1500 rpm no influence of gas−liquid mass transfer was observed. Hydrogen liquid−solid (L-S) mass transfer was found to be negligible, whereas the MBY mass L-S transfer becomes important at high MBY conversions at high hydrogen concentration. Low stirrer speed caused the reaction rate and MBE selectivity to decrease. No internal mass transfer limitations were observed, and conditions for the kinetic regime were found. The kinetics modeled followed the Langmuir−Hinshelwood mechanism and was consistent with the experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800070w [article] Three-phase catalytic hydrogenation of a functionalized alkyne : mass transfer and kinetic studies with in situ hydrogen monitoring [texte imprimé] / Andrea Bruehwiler, Auteur ; Natalia Semagina, Auteur ; Martin Grasemann, Auteur . - 2008 . - p. 6862–6869. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°18 (Septembre 2008) . - p. 6862–6869 Mots-clés : Mass  transfer  interactions  Hydrogen  Catalytic  hydrogenation Résumé : Systematic studies of mass transfer interactions with intrinsic reaction kinetics were performed for the three-phase selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE) over a modified Pd/CaCO3 catalyst under solvent free conditions. Hydrogen concentration in the liquid phase (CH2,b) was monitored in situ during the catalytic reaction by means of the “Fugatron” analyzer. Reactions were carried out in an autoclave at different stirring rates at two concentrations of hydrogen (5 and 13 mol·m−3). For stirring speeds higher than 1500 rpm no influence of gas−liquid mass transfer was observed. Hydrogen liquid−solid (L-S) mass transfer was found to be negligible, whereas the MBY mass L-S transfer becomes important at high MBY conversions at high hydrogen concentration. Low stirrer speed caused the reaction rate and MBE selectivity to decrease. No internal mass transfer limitations were observed, and conditions for the kinetic regime were found. The kinetics modeled followed the Langmuir−Hinshelwood mechanism and was consistent with the experimental data. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800070w