Documents disponibles écrits par cet auteur

Hydrogenation of a-methylstyrene in a piston-oscillating monolith reactor / Alan G. Bussard in Industrial & engineering chemistry research, Vol. 47 n°14 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4623-4631 Titre : Hydrogenation of a-methylstyrene in a piston-oscillating monolith reactor Type de document : texte imprimé Auteurs : Alan G. Bussard, Auteur ; Yogesh G. Waghmare, Auteur ; Kerry M Dooley, Auteur ; F Carl Knopf, Auteur Année de publication : 2008 Article en page(s) : p. 4623-4631 Note générale : Bibliogr. p. 4631 Langues : Anglais (eng) Mots-clés : A-methylstyrene  --  hydrogenation;  Piston-oscillating  monolith  reactor; Résumé : The hydrogenation of a-methylstyrene (AMS) to cumene was investigated in a novel piston-oscillating monolith reactor (POMR). Low-frequency (0-17.5 Hz) and -amplitude (2.5 mm) mechanical oscillations were applied to the three-phase system at 46 °C and 0.44 MPa of H2. For comparison purposes, the reaction was also carried out in a stirred tank at identical temperatures and pressures and at similar power input per volume. Results show activity improvements of up to 84% for 17.5 Hz, 2.5 mm piston oscillations over low-frequency gas flow pulsing conditions, and significantly greater improvements when compared to trickle beds or conventional monolith reactors. The POMR also gives as good or better selectivity toward cumene than a stirred tank at identical conditions. While the effects of catalyst pretreatment and its impact on the Pd crystallite size also have an important role in determining the catalyst activity and long-term stability in AMS hydrogenation, these results suggest that the impact of low-frequency and -amplitude oscillations, applied to structured reactors, is considerable. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701708w [article] Hydrogenation of a-methylstyrene in a piston-oscillating monolith reactor [texte imprimé] / Alan G. Bussard, Auteur ; Yogesh G. Waghmare, Auteur ; Kerry M Dooley, Auteur ; F Carl Knopf, Auteur . - 2008 . - p. 4623-4631. Bibliogr. p. 4631 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4623-4631 Mots-clés : A-methylstyrene  --  hydrogenation;  Piston-oscillating  monolith  reactor; Résumé : The hydrogenation of a-methylstyrene (AMS) to cumene was investigated in a novel piston-oscillating monolith reactor (POMR). Low-frequency (0-17.5 Hz) and -amplitude (2.5 mm) mechanical oscillations were applied to the three-phase system at 46 °C and 0.44 MPa of H2. For comparison purposes, the reaction was also carried out in a stirred tank at identical temperatures and pressures and at similar power input per volume. Results show activity improvements of up to 84% for 17.5 Hz, 2.5 mm piston oscillations over low-frequency gas flow pulsing conditions, and significantly greater improvements when compared to trickle beds or conventional monolith reactors. The POMR also gives as good or better selectivity toward cumene than a stirred tank at identical conditions. While the effects of catalyst pretreatment and its impact on the Pd crystallite size also have an important role in determining the catalyst activity and long-term stability in AMS hydrogenation, these results suggest that the impact of low-frequency and -amplitude oscillations, applied to structured reactors, is considerable. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie701708w

Mass transfer in a viscous bubble column with forced oscillations / Y. G. Waghmare in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5386-5394 Titre : Mass transfer in a viscous bubble column with forced oscillations Type de document : texte imprimé Auteurs : Y. G. Waghmare, Auteur ; Richard G. Rice, Auteur ; F Carl Knopf, Auteur Année de publication : 2008 Article en page(s) : p. 5386-5394 Note générale : Bibliogr. p. 5394 Langues : Anglais (eng) Mots-clés : Viscous  bubble  column;  Oscillations  --  mass  transfer;  carboxymethylcellulose  solutions Résumé : Previously, it was shown that low-amplitude (0.5−2.5 mm) oscillations at moderate frequencies (0−25 Hz) can be used to improve bubble column performance. Literature on pulsed-flow bubble columns has mainly focused on air−water systems. In the present work, the effects of oscillations on mass transfer in a pulsed-flow bubble column were studied for various carboxymethylcellulose solutions giving an effective viscosity range of 1−62 cP. As in our previous work on air−water systems, the viscous system exhibits an initial increase in mass-transfer coefficient as a function of frequency and then leveled to a plateau. This asymptotic behavior can be attributed to the Bjerknes force acting on a bubble, which slows the bubble rise as frequency is increased. The shape of the curve for mass-transfer coefficient vs frequency was unchanged for viscous systems, but the absolute value of the mass-transfer coefficient decreased as a function of increasing viscosity. A theory was developed from first principles to show how the volumetric mass-transfer coefficient changes as a function of operating parameters, such as the frequency and amplitude of vibrations, gas superficial velocity, and viscosity of the fluid. The comparison with experiments was quite good for a large range of velocities and viscosities. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800041k [article] Mass transfer in a viscous bubble column with forced oscillations [texte imprimé] / Y. G. Waghmare, Auteur ; Richard G. Rice, Auteur ; F Carl Knopf, Auteur . - 2008 . - p. 5386-5394. Bibliogr. p. 5394 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5386-5394 Mots-clés : Viscous  bubble  column;  Oscillations  --  mass  transfer;  carboxymethylcellulose  solutions Résumé : Previously, it was shown that low-amplitude (0.5−2.5 mm) oscillations at moderate frequencies (0−25 Hz) can be used to improve bubble column performance. Literature on pulsed-flow bubble columns has mainly focused on air−water systems. In the present work, the effects of oscillations on mass transfer in a pulsed-flow bubble column were studied for various carboxymethylcellulose solutions giving an effective viscosity range of 1−62 cP. As in our previous work on air−water systems, the viscous system exhibits an initial increase in mass-transfer coefficient as a function of frequency and then leveled to a plateau. This asymptotic behavior can be attributed to the Bjerknes force acting on a bubble, which slows the bubble rise as frequency is increased. The shape of the curve for mass-transfer coefficient vs frequency was unchanged for viscous systems, but the absolute value of the mass-transfer coefficient decreased as a function of increasing viscosity. A theory was developed from first principles to show how the volumetric mass-transfer coefficient changes as a function of operating parameters, such as the frequency and amplitude of vibrations, gas superficial velocity, and viscosity of the fluid. The comparison with experiments was quite good for a large range of velocities and viscosities. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800041k