Organosilicon-modified silicas as support for zirconocene catalyst

Santos, João Henrique Zimnoch dos; Greco, Paula Palmeira; Stedile, Fernanda Chiarello; Dupont, Jaı̈rton

doi:10.1016/s1381-1169(99)00393-3

Cited by 62 publications

(41 citation statements)

References 34 publications

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“…This behavior is in agreement with the reduction of the number of vicinal silanol groups that may deactivate the catalyst by the formation of bidentate species [33]. It is also clearly seen that activity reaches a maximum value, which is maintained along time on pristine MCM-41 and functionalized MCM-41-OES.…”

Section: A C C E P T E D Accepted Manuscriptsupporting

confidence: 81%

Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties

Cerrada

Bento

Pérez

et al. 2016

Microporous and Mesoporous Materials

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Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties, Microporous and Mesoporous Materials (2016), doi: 10.1016/j.micromeso.2016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Mechanical response is observed to be dependent on the content in mesoporous MCM-41 and on the crystalline features of polyethylene. Accordingly, stiffness increases and deformability decreases in the nanocomposites as much as MCM-41 content is enlarged and polyethylene amount within channels is raised. Ultimate mechanical performance improves with MCM-41 incorporation without varying the final processing temperature.

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Section: A C C E P T E D Accepted Manuscriptsupporting

confidence: 81%

Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties

Cerrada

Bento

Pérez

et al. 2016

Microporous and Mesoporous Materials

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“…Furthermore, SP-3 has a high surface area and a high porosity, which is helpful to distribute and stabilize the active species on the carrier against bimolecular catalyst deactivation processes, which can occur for supported zirconocene catalysts. [13] Therefore, high catalyst activity can be obtained with SPC-3. Different supports have a moderate effect on the branching of PEs, though the supported catalysts produce PEs with distinctly less total branching than the homogeneous catalyst.…”

Section: Effect Of Dealcoholization Temperature On Mgcl 2 Supportsmentioning

confidence: 99%

Preparation of Spherical MgCl₂‐Supported Late‐Transition Metal Catalysts for Ethylene Polymerization

Liu

Wang

et al. 2006

Macro Chemistry & Physics

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Summary: Facile and effective immobilization of late‐transition metal catalysts, 2,3‐bis‐(2,6‐diisopropylphenyl)butane diimine nickel(ii) dibromide (A) and 2,6‐bis‐[1‐(2,4,6‐trimethylphenylimino)ethyl]pyridine iron(ii) dichloride (B), for ethylene polymerization has been achieved, using spherical MgCl2 supports obtained by thermal dealcoholization of MgCl2 · 2.56C2H5OH instead of using supports of type MgCl2/AlRn(OEt)3−n. BET, XRD, IR, SEM, GPC, and DSC analyses indicate that the composition and structure of the supports, the activities of the supported catalysts, and the properties of the resultant polymers are strongly dependent on the dealcoholization temperature. The support SP‐3 obtained by treating MgCl2 · 2.56C2H5OH at 170 °C for 4 h is very effective for immobilizing late‐transition metal FeII and NiII catalysts. Compared with the corresponding unsupported homogeneous catalysts, a significant increase in activity is observed for the SP‐3 supported catalysts in ethylene polymerization, and the kinetics of polymerization is stable during the reaction process. In addition, replication of the support morphology is found in final polymers.Kinetic profiles of ethylene polymerization using SPC‐4, SPC‐5, and SPC‐6 under 1.0 MPa and at 70 °C.imageKinetic profiles of ethylene polymerization using SPC‐4, SPC‐5, and SPC‐6 under 1.0 MPa and at 70 °C.

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“…Esses sistemas catalíticos apresentam uma maior atividade atribuída à maior disponibilidade do sítio ativo, que se encontra mais afastado da superfície. 83 Agentes de modificação podem também ser adicionados para reduzir o número de hidroxilas disponíveis na superfície para a ligação do metaloceno. Nesse mé-todo, os metalocenos ficam mais distanciados entre si, diminuindo a possibilidade de desativação bimolecular e, por conseguinte, levando a um aumento da atividade do catalisador.…”

Section: Heterogeneização Do Metaloceno Sobre O Suporte Previamente Funclassified

“…Quando empregado dessa forma, o agente de modificação serve como um espaçador horizontal, conforme mostrado na Figura 5c. 83 Alguns suportes (SiO 2 , ZrO 2 e Al 2 O 3 ) são tratados quimicamente de forma a ter em sua superfície grupos sulfônicos e, assim, exibir um caráter ácido de Brönsted acentuadamente forte. Esse forte caráter ácido advém da maior eletronegatividade do S em relação ao metal original (Si, Zr ou Al nos exemplos apresentados), reduzindo a densidade eletrônica sobre o átomo de oxigênio, o que torna mais covalente a ligação S-O.…”

Section: Heterogeneização Do Metaloceno Sobre O Suporte Previamente Funclassified

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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Organosilicon-modified silicas as support for zirconocene catalyst

Cited by 62 publications

References 34 publications

Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties

Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties

Preparation of Spherical MgCl₂‐Supported Late‐Transition Metal Catalysts for Ethylene Polymerization

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

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Organosilicon-modified silicas as support for zirconocene catalyst

Cited by 62 publications

References 34 publications

Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties

Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties

Preparation of Spherical MgCl2‐Supported Late‐Transition Metal Catalysts for Ethylene Polymerization

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

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Preparation of Spherical MgCl₂‐Supported Late‐Transition Metal Catalysts for Ethylene Polymerization