Effect of hydrogen on ethylene polymerization using in-situ supported metallocene catalysts

Chu, Kyung-Jun; Soares, João B. P.; Penlidis, Alexander

doi:10.1002/(sici)1521-3935(20000301)201:5<552::aid-macp552>3.0.co;2-a

Cited by 59 publications

(52 citation statements)

References 7 publications

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“…However, for the case of copolymers, it is also very important to measure the chemical composition distribution (CCD) in order to get a more complete understanding of catalytic centers types and polymer properties. [26][27][28][29] Typically, temperature rising elution fractionation (TREF) or crystallization analysis fractionation (Crystaf) are used to determine the CCD of olefin copolymers. The effect of the support on copolymer microstructure can be useful to identify the number and/or type of active sites formed during supporting, and to determine the influence of carrier pore size on catalyst behavior and polymer properties.…”

Section: Introductionmentioning

confidence: 99%

“…Interestingly, supported metallocenes can produce copolymers with broad CCD, even if their MWD is narrow, depending on the supporting technique, support properties, and polymerization conditions. [26][27][28][29]31] Both MWD and CCD influence copolymer rheological and mechanical properties. [32] In this investigation, we compare three SBA-15 carriers and commercial silica as support for an olefin polymerization metallocene catalyst to determine the effect of the carrier structure and pore size on polymerization rate and polymer properties.…”

Section: Introductionmentioning

confidence: 99%

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Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Paredes¹,

Grieken²,

Carrero³

et al. 2011

Macro Chemistry & Physics

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The influence of the support architecture (structure and pore size) on the activity of MAO/(nBuCp)2ZrCl2 heterogeneous catalysts in the polymerization of ethylene and 1‐hexene is studied through the characterization of the polymers' microstructure. SBA‐15 silica‐based mesostructured materials are synthesized with different pore sizes and compared with commercial silica. All SBA‐15 supported catalysts lead to higher catalytic activities than amorphous silica and give rise to ethylene/1‐hexene copolymers with bimodal CCD, which suggests that the carrier structure plays an important role not only in the global rate of the process but also in the copolymer composition. The structures and pore sizes of the support show a marked influence on the polymer CCD shape. magnified image

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Paredes¹,

Grieken²,

Carrero³

et al. 2011

Macro Chemistry & Physics

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“…The in-situ polymerization was originally conceived and published in 2000 by Soares et al [17,18]. Both approaches will be applied to overcome the above-listed problems and ensure approximately comparable hydrodynamics and macro-mixing (which are very important).…”

Section: Article In Pressmentioning

confidence: 99%

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

Adamu

Atiqullah

Malaibari

et al. 2016

Journal of the Taiwan Institute of Chemical Engineers

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Keywords:Metallocene catalyst Pseudo-homogeneous and in-situ heterogeneous isomeric ethylene−α-olefin copolymerization Hydrodynamic boundary layer mass transfer Inter-and intra-chain backbone composition distribution Lamellar thickness distribution Thermal properties a b s t r a c t This study reports a novel conceptual framework that can be easily experimented to evaluate the effects of hydrodynamic boundary layer mass transfer, methylaluminoxane (MAO) anion design, and comonomer steric hindrance on metallocene-catalyzed ethylene polymerization. This approach was illustrated by conducting homo-and isomeric copolymerization of ethylene with 1-hexene and 4-methyl-1-pentene in the presence of bis(n-butylcyclopentadienyl) zirconium dichloride ( n BuCp) 2 ZrCl 2 , using (i) MAO anion 1 (unsupported [MAOCl 2 ] − ) and pseudo-homogeneous reference polymerization, and (ii) MAO anion 2 (supported Si−O−[MAOCl 2 ] − ) and in-situ heterogeneous polymerization. The measured polymer morphology, catalyst productivity, molecular weight distribution, and inter-chain composition distribution were related to the locus of polymerization, comonomer effect, in-situ chain transfer process, and micromixing effect, respectively. The peak melting and crystallization temperatures and %crystallinity were mathematically correlated to the parameters of microstructural composition distributions, melt fractionation temperatures, and average lamellar thickness. These relations showed to be insightful. The comonomer-induced enchainment defects and the eventual partial disruption of the crystal lattice were successfully modeled using Flory and GibbsThompson equations. The present methodology can also be applied to study ethylene−α-olefin copolymerization, performed using MAO-activated non-metallocene precatalysts.

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“…Entretanto, Chu, Soares e Penlides 92 propuseram um método alternativo, pelo qual a imobilização do metaloceno é realizada diretamente no reator de polimerização usando sílica pré-tratada com MAO. De forma geral, não há necessidade de uma adição extra de MAO (denominado MAO externo) para atingir atividade catalítica elevada.…”

Section: Heterogeneização De Metalocenos In Situunclassified

Catalisadores metalocênicos suportados para a produção de poliolefinas: revisão das estratégias de imobilização

Fisch¹,

Cardozo²,

Secchi³

et al. 2011

Quím. Nova

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Recebido em 19/4/10; aceito em 13/11/10; publicado na web em 18/2/11 SUPPORTED METALLOCENE CATALYSTS FOR POLYOLEFIN PRODUCTION: REVIEW OF THE IMMOBILIZATION STRATEGIES. The inadequacy of strategies used for the heterogeneization of metallocene catalysts is pointed out as one of the main causes of the lack of industrial employability of such polymerization catalysts. The main problems are the necessity of large quantity of MAO (cocatalyst) and the inability to control molecular mass distribution of the polymers. Based on this background, the main strategies for the heterogeneization of metallocenes are here reviewed. The advantages and disadvantages of each strategy are presented and discussed on theoretical and practical perspective. Considering the results reported on the different researches, outcomes of heterogeneization strategies are pointed out.Keywords: supported metallocene; polymerization; heterogeneous catalysis. INTRODUÇÃOCatalisadores para a produção de poliolefinas têm sido continuamente estudados desde o advento dos catalisadores Ziegler-Natta. Ao longo desses esforços, diferentes tipos de complexos foram investigados, dentre eles os metalocenos. Pertencente a essa classe, o titanoceno (Cp 2 TiCl 2 ) foi estudado por volta de 1950 na polimerização de olefinas utilizando-se um alquil alumínio para sua ativação. Nesses estudos, a atividade catalítica encontrada não foi suficientemente alta (>100 g pol g cat -1 h -1 ) para justificar maiores investimentos em pesquisas relacionadas a esses complexos. A aplicação industrial desses catalisadores tornou-se possível somente após as pesquisas de Sinn e Kaminsky 1 no final da década de 70, com a descoberta do papel cocatalítico do metilaluminoxano (MAO), gerado a partir da hidrólise parcial do trimetil alumínio (TMA). O sistema resultante metaloceno/MAO mostrou-se dotado de elevada atividade catalítica, até então não atingível com alquil alumínios comuns no papel de cocatalisadores. A partir desse momento, teve então início uma intensa atividade de pesquisa industrial e acadêmica buscando solucionar outros problemas relacionados à adaptação dos metalocenos às plantas industriais de polimerização já existentes, que operam com catalisadores Ziegler-Natta heterogêneos, em sua grande maioria. Aliado a isso, pesquisas voltaram-se ao desenvolvimento de novos complexos organometálicos, metalocênicos e não metalocêni-cos (os denominados pós-metalocenos), passíveis de produzir novos materiais poliméricos. [2][3][4][5][6][7] A Figura 1 ilustra o desenvolvimento das pesquisas para os catalisadores Ziegler-Natta, metalocenos e não metalocenos em termos do número anual de publicações. A Figura 1a mostra claramente o crescimento gradual das pesquisas envolvendo catalisadores Ziegler-Natta a partir do início da década de 60, atingindo um patamar nos meados da década de 80 e mantendo-se relativamente constante desde então. A Figura 1b evidencia o crescimento exponencial das pesquisas com foco nos complexos metalocênicos após a descoberta do MAO como cocatalisador, no final ...

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Effect of hydrogen on ethylene polymerization using in-situ supported metallocene catalysts

Cited by 59 publications

References 7 publications

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

Catalisadores metalocênicos suportados para a produção de poliolefinas: revisão das estratégias de imobilização

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Effect of hydrogen on ethylene polymerization using in-situ supported metallocene catalysts

Cited by 59 publications

References 7 publications

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)2ZrCl2 Supported on SBA‐15 Materials with Different Pore Sizes

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)2ZrCl2 Supported on SBA‐15 Materials with Different Pore Sizes

Metallocene-catalyzed ethylene−α-olefin isomeric copolymerization: A perspective from hydrodynamic boundary layer mass transfer and design of MAO anion

Catalisadores metalocênicos suportados para a produção de poliolefinas: revisão das estratégias de imobilização

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Product

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Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes

Ethylene/1‐Hexene Copolymers Produced with MAO/(nBuCp)₂ZrCl₂ Supported on SBA‐15 Materials with Different Pore Sizes