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Dynamic Modeling of a Moving-Packed-Bed Reactor for the Solid-State Polymerization of Bisphenol-A Polycarbonate / Yuesheng Ye in Industrial & engineering chemistry research, Vol. 47 N°10 (Mai 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3687-3699 Titre : Dynamic Modeling of a Moving-Packed-Bed Reactor for the Solid-State Polymerization of Bisphenol-A Polycarbonate Type de document : texte imprimé Auteurs : Yuesheng Ye, Auteur ; Kyu Yong Choi, Auteur Année de publication : 2008 Article en page(s) : p. 3687-3699 Langues : Anglais (eng) Mots-clés : Dynamic  Modeling  ;  Polymerization  ;  Polycarbonate Résumé : A dynamic process model has been developed for a continuous solid-state step-growth polymerization of bisphenol-A polycarbonate in a moving-packed-bed reactor. In this process, the molecular weight of polycarbonate prepolymer particles is increased as they move downward in a vertical reactor. A heated purge gas is supplied to the bottom of the reactor and flows upward at a high flow rate to remove volatile condensates from the polymer particles and provide thermal energy for the solid-state polymerization. A macroscopic reactor model and a polymer particle model are combined and solved together to calculate the reactor temperature profiles and the polymer-molecular-weight properties. The effects of reactor design and operation parameters on the performance of the solid-state polymerization reactor are analyzed through model simulations. It is shown that a large-scale moving-packed-bed reactor can have a significant temperature nonuniformity in the reactor, particularly during the startup operation, affecting the uniformity of the molecular weight of the polymer in the product. En ligne : https://pubs.acs.org/doi/abs/10.1021/ie071078s [article] Dynamic Modeling of a Moving-Packed-Bed Reactor for the Solid-State Polymerization of Bisphenol-A Polycarbonate [texte imprimé] / Yuesheng Ye, Auteur ; Kyu Yong Choi, Auteur . - 2008 . - p. 3687-3699. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°10 (Mai 2008) . - p. 3687-3699 Mots-clés : Dynamic  Modeling  ;  Polymerization  ;  Polycarbonate Résumé : A dynamic process model has been developed for a continuous solid-state step-growth polymerization of bisphenol-A polycarbonate in a moving-packed-bed reactor. In this process, the molecular weight of polycarbonate prepolymer particles is increased as they move downward in a vertical reactor. A heated purge gas is supplied to the bottom of the reactor and flows upward at a high flow rate to remove volatile condensates from the polymer particles and provide thermal energy for the solid-state polymerization. A macroscopic reactor model and a polymer particle model are combined and solved together to calculate the reactor temperature profiles and the polymer-molecular-weight properties. The effects of reactor design and operation parameters on the performance of the solid-state polymerization reactor are analyzed through model simulations. It is shown that a large-scale moving-packed-bed reactor can have a significant temperature nonuniformity in the reactor, particularly during the startup operation, affecting the uniformity of the molecular weight of the polymer in the product. En ligne : https://pubs.acs.org/doi/abs/10.1021/ie071078s

Polymerization of ethylene over rac - Et(1 - indenyl)2ZrCl2/MAO catalyst supported on pseudo - inverse opal silica particles / Sang Yool Lee in Industrial & engineering chemistry research, Vol. 51 N° 29 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 29 (Juillet 2012) . - pp. 9742-9749 Titre : Polymerization of ethylene over rac - Et(1 - indenyl)2ZrCl2/MAO catalyst supported on pseudo - inverse opal silica particles Type de document : texte imprimé Auteurs : Sang Yool Lee, Auteur ; Kyu Yong Choi, Auteur Année de publication : 2012 Article en page(s) : pp. 9742-9749 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalyst  support  Polymerization Résumé : The polymerization of ethylene with rac-Et(1-indenyl)2ZrCl2/MAO catalyst supported on ultraporous and spherical pseudo-inverse opal silica (PIOS) particles with unique morphology is reported. The novel silica particles with an inverse opal-like structure provide wide-open pore and surface structures favorable for the catalyst deposition and monomer access with minimal intraparticle diffusion resistance. The metallocene catalyst supported on the PIOS support exhibited very high initial catalyst activity and longer catalyst lifetime compared with conventional silica-supported catalysts. The experimental data that show the effects of support geometry on the catalytic activity, catalyst particle fragmentation, polymer particle morphology, and polymer molecular weight distribution in ethylene polymerization are presented. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26184952 [article] Polymerization of ethylene over rac - Et(1 - indenyl)2ZrCl2/MAO catalyst supported on pseudo - inverse opal silica particles [texte imprimé] / Sang Yool Lee, Auteur ; Kyu Yong Choi, Auteur . - 2012 . - pp. 9742-9749. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 29 (Juillet 2012) . - pp. 9742-9749 Mots-clés : Catalyst  support  Polymerization Résumé : The polymerization of ethylene with rac-Et(1-indenyl)2ZrCl2/MAO catalyst supported on ultraporous and spherical pseudo-inverse opal silica (PIOS) particles with unique morphology is reported. The novel silica particles with an inverse opal-like structure provide wide-open pore and surface structures favorable for the catalyst deposition and monomer access with minimal intraparticle diffusion resistance. The metallocene catalyst supported on the PIOS support exhibited very high initial catalyst activity and longer catalyst lifetime compared with conventional silica-supported catalysts. The experimental data that show the effects of support geometry on the catalytic activity, catalyst particle fragmentation, polymer particle morphology, and polymer molecular weight distribution in ethylene polymerization are presented. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26184952

Reduction of bisphenol A residue in polycarbonates in a two-stage step-growth polymerization process / Yuesheng Ye in Industrial & engineering chemistry research, Vol. 48 N° 9 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4274–4282 Titre : Reduction of bisphenol A residue in polycarbonates in a two-stage step-growth polymerization process Type de document : texte imprimé Auteurs : Yuesheng Ye, Auteur ; Kyu Yong Choi, Auteur Année de publication : 2009 Article en page(s) : pp. 4274–4282 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polycondensation  process  Bisphenol  A  Bisphenol  A  polycarbonate Résumé : A theoretical modeling and simulation study is presented for the design of operational policies for a two-stage polycondensation process to achieve a significant reduction of bisphenol A (BPA) residue in high molecular weight bisphenol A polycarbonate (BAPC). In the first stage, low molecular weight polycarbonate prepolymers are prepared in a semibatch melt transesterification reactor under reduced pressure, and in the second stage, a solid-state polymerization is used to further increase the polymer molecular weight and to reduce the BPA residue. The residual BPA concentration in the final polymer can be significantly reduced by employing an optimally determined excess amount of diphenyl carbonate (DPC) in the transesterification stage. However, there is a narrow window of operating conditions that will satisfy the multiple process requirements of the lowest BPA concentration, high molecular weight, and economically feasible short reaction time. The proposed method can also be applied to optimally blending prepolymers of different reactive end group concentrations for the subsequent solid-state polymerization to reduce the BPA content and to obtain high molecular weight. The proposed methods are illustrated through model simulations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014318 [article] Reduction of bisphenol A residue in polycarbonates in a two-stage step-growth polymerization process [texte imprimé] / Yuesheng Ye, Auteur ; Kyu Yong Choi, Auteur . - 2009 . - pp. 4274–4282. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4274–4282 Mots-clés : Polycondensation  process  Bisphenol  A  Bisphenol  A  polycarbonate Résumé : A theoretical modeling and simulation study is presented for the design of operational policies for a two-stage polycondensation process to achieve a significant reduction of bisphenol A (BPA) residue in high molecular weight bisphenol A polycarbonate (BAPC). In the first stage, low molecular weight polycarbonate prepolymers are prepared in a semibatch melt transesterification reactor under reduced pressure, and in the second stage, a solid-state polymerization is used to further increase the polymer molecular weight and to reduce the BPA residue. The residual BPA concentration in the final polymer can be significantly reduced by employing an optimally determined excess amount of diphenyl carbonate (DPC) in the transesterification stage. However, there is a narrow window of operating conditions that will satisfy the multiple process requirements of the lowest BPA concentration, high molecular weight, and economically feasible short reaction time. The proposed method can also be applied to optimally blending prepolymers of different reactive end group concentrations for the subsequent solid-state polymerization to reduce the BPA content and to obtain high molecular weight. The proposed methods are illustrated through model simulations. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8014318