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Skeletal isomerization of butene in fixed beds. 1. experimental investigation and structure-performance effects / Matias Kangas 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. 5402–5412 Titre : Skeletal isomerization of butene in fixed beds. 1. experimental investigation and structure-performance effects Type de document : texte imprimé Auteurs : Matias Kangas, Auteur ; Narendra Kumar, Auteur ; Elina Harlin, Auteur Année de publication : 2008 Article en page(s) : p. 5402–5412 Note générale : Bibliogr. p. 5412 Langues : Anglais (eng) Mots-clés : Skeletal  isomerization  --  structure-performance;  Butene Résumé : An experimental investigation of structure-performance effects in zeolite catalyzed skeletal isomerization has been carried out. Two structurally different, medium-pore-size zeolites (H-TON and H-FER) with similar acidities were compared in butene skeletal isomerization. While both catalysts proved to be efficient in the test reaction, their deactivation behavior differed substantially. H-FER exhibited significantly higher initial isobutene yields and selectivities, and the catalyst performance was also more stable with time-on-stream. H-TON, on the other hand, needed prolonged operation times in order to achieve product distributions comparable to those of H-FER. The predominant route to isobutene was found to be the monomolecular one, with the bimolecular paths of butene largely responsible for byproduct formation. H-TON was more selective toward disproportionation and, owing to its slightly larger pore dimensions, hydrogen transfer products. H-TON was also observed to be less sensitive to feed reactant than H-FER was, confirming previous theoretically calculated structure effects. Coke belonging to both aliphatic and aromatic families was detected over both zeolites, although the coke formed on H-FER was overall heavier and more aromatic in nature. The tested zeolites could be regenerated by burning of the carbonaceous deposits in air, and both catalysts regained almost all of their initial activities. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800061q [article] Skeletal isomerization of butene in fixed beds. 1. experimental investigation and structure-performance effects [texte imprimé] / Matias Kangas, Auteur ; Narendra Kumar, Auteur ; Elina Harlin, Auteur . - 2008 . - p. 5402–5412. Bibliogr. p. 5412 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5402–5412 Mots-clés : Skeletal  isomerization  --  structure-performance;  Butene Résumé : An experimental investigation of structure-performance effects in zeolite catalyzed skeletal isomerization has been carried out. Two structurally different, medium-pore-size zeolites (H-TON and H-FER) with similar acidities were compared in butene skeletal isomerization. While both catalysts proved to be efficient in the test reaction, their deactivation behavior differed substantially. H-FER exhibited significantly higher initial isobutene yields and selectivities, and the catalyst performance was also more stable with time-on-stream. H-TON, on the other hand, needed prolonged operation times in order to achieve product distributions comparable to those of H-FER. The predominant route to isobutene was found to be the monomolecular one, with the bimolecular paths of butene largely responsible for byproduct formation. H-TON was more selective toward disproportionation and, owing to its slightly larger pore dimensions, hydrogen transfer products. H-TON was also observed to be less sensitive to feed reactant than H-FER was, confirming previous theoretically calculated structure effects. Coke belonging to both aliphatic and aromatic families was detected over both zeolites, although the coke formed on H-FER was overall heavier and more aromatic in nature. The tested zeolites could be regenerated by burning of the carbonaceous deposits in air, and both catalysts regained almost all of their initial activities. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800061q

Skeletal isomerization of butene in fixed beds. part 2. kinetic and flow modeling / Matias Kangas 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. 5413–5426 Titre : Skeletal isomerization of butene in fixed beds. part 2. kinetic and flow modeling Type de document : texte imprimé Auteurs : Matias Kangas, Auteur ; Tapio Salmi, Auteur ; Dmitry Yu. Murzin, Auteur Année de publication : 2008 Article en page(s) : p. 5413–5426 Note générale : Bibliogr. p. 5325-5326 Langues : Anglais (eng) Mots-clés : Zeolite  catalyzed  hydrocarbon  --  packed  bed;  Butene  --  skeletal  isomerization Résumé : Starting from detailed experimental studies of reaction kinetics, catalyst deactivation, and reactor flow conditions, mathematical models describing the dynamic reactor performance in zeolite catalyzed hydrocarbon transformations in packed beds have been developed. By using a sequential calculation procedure that involved changes in reactor models, solvers, and optimizers, kinetic parameters were regressed for two promising catalysts. Utilizing the estimated parameters and the developed kinetic and flow models, the skeletal isomerization of n-butene was accurately modeled. A proper description of adsorption and deactivation was shown to be as important as the kinetic formulation itself in obtaining good fits to the experimental results. Separable kinetics and deactivation functions were used. Relating the activity of the catalysts to the fraction of noncoked zeolite surface predicted the measured specific surface area to within 5-10%, indicating that reaction takes place throughout the whole catalyst pellet. Structure effects were observed in the estimated composite kinetic parameters. Protonated cyclopropane branching was much easier over H-FER, whereas n-butene codimerization with isobutene was significantly more facile over H-TON. Similar composite activation energies for the β-scission steps were obtained for both zeolites. The estimated reaction enthalpies for the oligomerization-cracking surface reaction were substantially lower than the thermodynamically calculated heats of reaction for the corresponding gas phase reactions, suggesting that olefin addition proceeds via the stepwise oligomerization mechanism. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800062m [article] Skeletal isomerization of butene in fixed beds. part 2. kinetic and flow modeling [texte imprimé] / Matias Kangas, Auteur ; Tapio Salmi, Auteur ; Dmitry Yu. Murzin, Auteur . - 2008 . - p. 5413–5426. Bibliogr. p. 5325-5326 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5413–5426 Mots-clés : Zeolite  catalyzed  hydrocarbon  --  packed  bed;  Butene  --  skeletal  isomerization Résumé : Starting from detailed experimental studies of reaction kinetics, catalyst deactivation, and reactor flow conditions, mathematical models describing the dynamic reactor performance in zeolite catalyzed hydrocarbon transformations in packed beds have been developed. By using a sequential calculation procedure that involved changes in reactor models, solvers, and optimizers, kinetic parameters were regressed for two promising catalysts. Utilizing the estimated parameters and the developed kinetic and flow models, the skeletal isomerization of n-butene was accurately modeled. A proper description of adsorption and deactivation was shown to be as important as the kinetic formulation itself in obtaining good fits to the experimental results. Separable kinetics and deactivation functions were used. Relating the activity of the catalysts to the fraction of noncoked zeolite surface predicted the measured specific surface area to within 5-10%, indicating that reaction takes place throughout the whole catalyst pellet. Structure effects were observed in the estimated composite kinetic parameters. Protonated cyclopropane branching was much easier over H-FER, whereas n-butene codimerization with isobutene was significantly more facile over H-TON. Similar composite activation energies for the β-scission steps were obtained for both zeolites. The estimated reaction enthalpies for the oligomerization-cracking surface reaction were substantially lower than the thermodynamically calculated heats of reaction for the corresponding gas phase reactions, suggesting that olefin addition proceeds via the stepwise oligomerization mechanism. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800062m