Activator Supports for Metallocene and Related Catalysts

Hoff, R.

doi:10.1002/9781119242277.ch3

Cited by 15 publications

(19 citation statements)

References 8 publications

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“…This has been observed not only in the (pyridylamido)Hf(IV) catalyst but also in other group 4 metal complexes such as Kaminsky catalysts. − Hence, the mechanisms of the polymerization reactions of Kaminsky catalysts with these CAs have been intensively studied so far by experimental − and theoretical methods. − It is a well-established fact that weakly coordinating CAs can facilitate monomer coordination, leading to higher catalytic activity. ,,,− It was also suggested that the monomer capture process plays an important role in determining the polymerization reaction rate, and CAs are likely to be relevant in this process . However, among the previous computational studies, only a few theoretical studies have focused on the dynamic aspect of the effect of CAs. − Therefore, it would be valuable to conduct a comprehensive study on the polymerization reaction mechanism by using both quantum mechanics (QM) and molecular dynamics (MD) methods to reveal the microscopic origin of the different reaction rates depending on the CAs.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Elucidation of the Effect of Counteranions on the Olefin Polymerization Activity of (Pyridylamido)Hf(IV) Catalyst by QM and REMD Studies: MeB(C₆F₅)₃^– versus B(C₆F₅)₄^–

et al. 2020

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1-Octene insertion reaction by the cationic active species of (pyridylamido)Hf(IV) catalyst (HfCat+) was investigated, focusing on the effect of the counteranions (CAs), MeB(C6F5)3 – and B(C6F5)4 – on catalyst activity. Quantum mechanical (QM) calculation showed a remarkable difference in TS structures that HfCat+–MeB(C6F5)3 – complex forms an “inner-sphere” ion pair (ISIP), while HfCat+–B(C6F5)4 – forms an “outer-sphere” ion pair (OSIP). However, the activation free energies of 1-octene insertion by both complexes are almost identical to each other. Meanwhile, replica exchange molecular dynamics (REMD) calculation revealed that the time duration of the HfCat+ capturing 1-octene monomers throughout the REMD trajectories of HfCat+–B(C6F5)4 – complex was ∼2.5 times that of HfCat+–MeB(C6F5)3 –. This is because B(C6F5)4 – is more likely to dissociate from HfCat+ to form an OSIP than MeB(C6F5)3 – and thus allows monomers to approach HfCat+ more easily. Using these microscopic data, we have numerically evaluated the 1-octene polymerization reaction rate constants and succeeded in qualitatively reproducing the experimentally observed tendency of the polymerization reaction with B(C6F5)4 – faster than with MeB(C6F5)3 –. Finally, it is theoretically elucidated that the monomer capture process before the monomer insertion process determines the overall polymerization reaction rates in this catalytic system.

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Section: Introductionmentioning

confidence: 99%

Theoretical Elucidation of the Effect of Counteranions on the Olefin Polymerization Activity of (Pyridylamido)Hf(IV) Catalyst by QM and REMD Studies: MeB(C₆F₅)₃^– versus B(C₆F₅)₄^–

et al. 2020

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“…The supported catalyst precursors were tested for their ability to polymerize ethylene, showing relatively good catalytic activity and controlled particle size when the activation was carried out using DEAC as a cocatalyst. The controlled particle morphology and the absence of reactor fouling are distinctive signatures of the use of heterogeneous catalysts during ethylene polymerizations, providing additional evidence for the anchoring of complex 1 on the silica surface. ,, This study aimed to provide a proof-of-concept of the possibility to immobilize an arylimido–vanadium(V) complex on silica supports to obtain PE with controlled particle size. The polymers were analyzed using melt rheology, which does not show any tendency to full relaxation at significantly low frequencies (high relaxation time), which in turn can be translated into high molecular weight (well above 1 million g mol −1 ).…”

Section: Discussionmentioning

confidence: 99%

Immobilization of [VCl₃(N-2,6-Me₂C₆H₃)] Complex on Silica Supports: Synthesis and Catalytic Testing for Ethylene Polymerization

Fiorentino

Panariti

Turnhout

et al. 2020

Ind. Eng. Chem. Res.

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The heterogenization of 2,6-dimethylarylimido–vanadium(V) dichloride via chemical tethering on insoluble silica supports is reported. The effects of the silica particle size, drying conditions, and the reaction time were investigated. The drying conditions of the support were found to be a crucial parameter: drying temperatures over 400 °C were needed to achieve successful catalysis. The supported catalytic systems were characterized by Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy–energy-dispersive X-ray (TEM-EDX), and inductively coupled plasma mass spectroscopy (ICP-MS), while the polymers were characterized by FT-IR, differential scanning calorimetry (DSC), and rheology. Ethylene polymerization tests were performed employing the prepared heterogenized catalysts with methylaluminoxane/diethylaluminum chloride as a cocatalyst. The supported catalyst precursor, when activated with diethylaluminum chloride, promotes the synthesis of polyethylene with seemingly controlled particle size in the absence of reactor fouling, suggesting the successful immobilization of the complex over the inert support. The resulting polymer shows features of ultrahigh-molecular-weight polyethylene (UHMWPE). These findings present a proof-of-concept for a new approach toward the heterogenization of arylimido–vanadium complexes.

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“…Among many different catalytic systems, heterogeneous Ziegler-Natta catalysts represent the most significant in the polyolefin industry in the context of both extremally high catalytic efficiency and low-cost production [ 92 ]. Generally, catalytic systems contain titanium coordination compounds immobilized on MgCl 2 support activated by trialkyl aluminum.…”

Section: Cage-like Silsesquioxanes In Materials Engineeringmentioning

confidence: 99%

A Brief Review on Selected Applications of Hybrid Materials Based on Functionalized Cage-like Silsesquioxanes

John

Ejfler

2023

Polymers

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Rapid developments in materials engineering are accompanied by the equally rapid development of new technologies, which are now increasingly used in various branches of our life. The current research trend concerns the development of methods for obtaining new materials engineering systems and searching for relationships between the structure and physicochemical properties. A recent increase in the demand for well-defined and thermally stable systems has highlighted the importance of polyhedral oligomeric silsesquioxane (POSS) and double-decker silsesquioxane (DDSQ) architectures. This short review focuses on these two groups of silsesquioxane-based materials and their selected applications. This fascinating field of hybrid species has attracted considerable attention due to their daily applications with unique capabilities and their great potential, among others, in biomaterials as components of hydrogel networks, components in biofabrication techniques, and promising building blocks of DDSQ-based biohybrids. Moreover, they constitute attractive systems applied in materials engineering, including flame retardant nanocomposites and components of the heterogeneous Ziegler-Natta-type catalytic system.

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Activator Supports for Metallocene and Related Catalysts

Cited by 15 publications

References 8 publications

Theoretical Elucidation of the Effect of Counteranions on the Olefin Polymerization Activity of (Pyridylamido)Hf(IV) Catalyst by QM and REMD Studies: MeB(C₆F₅)₃^– versus B(C₆F₅)₄^–

Theoretical Elucidation of the Effect of Counteranions on the Olefin Polymerization Activity of (Pyridylamido)Hf(IV) Catalyst by QM and REMD Studies: MeB(C₆F₅)₃^– versus B(C₆F₅)₄^–

Immobilization of [VCl₃(N-2,6-Me₂C₆H₃)] Complex on Silica Supports: Synthesis and Catalytic Testing for Ethylene Polymerization

A Brief Review on Selected Applications of Hybrid Materials Based on Functionalized Cage-like Silsesquioxanes

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Activator Supports for Metallocene and Related Catalysts

Cited by 15 publications

References 8 publications

Theoretical Elucidation of the Effect of Counteranions on the Olefin Polymerization Activity of (Pyridylamido)Hf(IV) Catalyst by QM and REMD Studies: MeB(C6F5)3– versus B(C6F5)4–

Theoretical Elucidation of the Effect of Counteranions on the Olefin Polymerization Activity of (Pyridylamido)Hf(IV) Catalyst by QM and REMD Studies: MeB(C6F5)3– versus B(C6F5)4–

Immobilization of [VCl3(N-2,6-Me2C6H3)] Complex on Silica Supports: Synthesis and Catalytic Testing for Ethylene Polymerization

A Brief Review on Selected Applications of Hybrid Materials Based on Functionalized Cage-like Silsesquioxanes

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Product

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Theoretical Elucidation of the Effect of Counteranions on the Olefin Polymerization Activity of (Pyridylamido)Hf(IV) Catalyst by QM and REMD Studies: MeB(C₆F₅)₃^– versus B(C₆F₅)₄^–

Theoretical Elucidation of the Effect of Counteranions on the Olefin Polymerization Activity of (Pyridylamido)Hf(IV) Catalyst by QM and REMD Studies: MeB(C₆F₅)₃^– versus B(C₆F₅)₄^–

Immobilization of [VCl₃(N-2,6-Me₂C₆H₃)] Complex on Silica Supports: Synthesis and Catalytic Testing for Ethylene Polymerization