Polymerization of Ethylene with Zirconocene Heterogenized on Spherical ZSM-5

Favero, Cristiano; Mignoni, Marcelo Luís; Souza, Roberto Fernando de; Bernardo-Gusmão, Kátia

doi:10.5935/0103-5053.20150109

Cited by 3 publications

(4 citation statements)

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“…However, for them to be employed industrially in existing gas phase and slurry processes, they need to be supported on a solid material [4] . A wide variety of solids can be used for this purpose, from the more commonly chosen inorganic supports as is the case of silica [1] , alumina [5,6] , zeolites [7,8] , clays [9,10] , magnesium chloride [11,12] or even polymeric MAO, [13] to organic supports such as starch [14] , cyclodextrin [15,16] and synthetic polymers [17,18] . When considering commodity polyolefins, silica is perhaps the most commonly employed support.…”

Section: Introductionmentioning

confidence: 99%

Innovative route for the preparation of high-performance polyolefin materials based on unique dendrimeric silica particles

et al. 2021

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Section: Introductionmentioning

confidence: 99%

Innovative route for the preparation of high-performance polyolefin materials based on unique dendrimeric silica particles

et al. 2021

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“…The total molar mass in the liquid is obtained by the difference with respect to the total molar amount. (17) The factions yi and xi are calculated by Equation (17) and (18), respectively (18) (19) The total moles in liquid phase nL, Equation (21), is obtained from the mass balances of toluene, Equation (19), and ethylene, Equation (20), in the both phases.…”

Section: Liquid-vapor Equilibrium (Lve)mentioning

confidence: 99%

“…The results were compared with those using the more traditional Zr dichloro complexes, finding higher activity in the first ones. [17] Zeolites [18] and solid polymethylaluminoxane [19] are among the supports reported for carrying out ethylene polymerizations catalyzed by Zr-based metallocenes, achieving high catalytic activities, high molecular weights, and narrow distributions. Although these works provide general features about the influence of the alkyl groups on the ligand substituents, and also the influence of using solid supports during the polymerization, they were all carried out using MAO as the activator.…”

Section: Introductionmentioning

confidence: 99%

Ethylene Polymerization via Zirconocene Catalysts and Organoboron Activators: An Experimental and Kinetic Modeling Study

Valencia¹,

Enríquez-Medrano²,

López-González³

et al. 2020

Preprint

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After 40 years of the discovery of metallocene catalysts, there are still several aspects that remain unresolved, especially when the “conventional” alkylaluminum activators are not used. Herein, we systematically investigate the synthesis of PE via three different zirconocene catalysts, with different alkyl substituents, activated via different organoboron compounds. The polymerization behavior, as well as the properties of the materials, are evaluated. The results demonstrate that the highest catalytic activity is shown by Bis(cyclopentadienyl)dimethylzirconium activated by trityl tetra(pentafluorophenyl)borate. Also finding that toluene is the optimum solvent for these systems and at these reaction conditions. Moreover, to validate our experimental results, a comprehensive mathematical model is developed on the basis of thermodynamic and kinetic principles. The concentration of ethylene transferred to the solvent phase (toluene) in a liquid-vapor equilibrium (LVE) system is estimated based on the Duhem’s theorem. Arrhenius expressions for the kinetic rate constants of a proposed kinetic mechanism are estimated by a kinetic model, in which the rate of polymerization is fitted by a least-square optimization procedure and the molecular weight averages by the method of moments. The simulations of the coordination polymerization suggest the presence of two types of active sites, principally at low temperatures, and the reactivation of the deactivated sites via a boron-based activator. However, the effect of the temperature on the reactivation step is no clear; a deeper understanding via designed experiments is required.

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“…The results were compared with those using the more traditional Zr dichloro complexes, finding higher activity in the former [17]. Zeolites (ZSM-5) [18], and solid polymethylaluminoxane [19] are among the supports reported for carrying out ethylene polymerizations catalyzed by Zr-based metallocenes, achieving high catalytic activities, high molecular weights, and narrow distributions. Although these works provide general features about the influence of the alkyl groups on the ligand substituents, and the influence of using solid supports during the polymerization, they were all carried out using MAO as the activator.…”

Section: Introductionmentioning

confidence: 99%

Ethylene Polymerization via Zirconocene Catalysts and Organoboron Activators: An Experimental and Kinetic Modeling Study

et al. 2021

View full text Add to dashboard Cite

Forty years after the discovery of metallocene catalysts, there are still several aspects that remain unresolved, especially when the “conventional” alkylaluminum activators are not used. Herein, we systematically investigated the synthesis of polyethylene (PE) via three different zirconocene catalysts, with different alkyl substituents, activated via different organoboron compounds. The polymerization behavior, as well as the properties of the materials, were evaluated. The results demonstrate that the highest catalytic activity is shown by bis(cyclopentadienyl)dimethylzirconium activated by trityl tetra(pentafluorophenyl)borate. Additionally, it was found that toluene is the optimum solvent for these systems and at these reaction conditions. Moreover, to validate our experimental results, a comprehensive mathematical model was developed on the basis of thermodynamic and kinetic principles. The concentration of ethylene transferred to the solvent phase (toluene) in a liquid–vapor equilibrium (LVE) system was estimated based on Duhem’s theorem. Arrhenius expressions for the kinetic rate constants of a proposed kinetic mechanism were estimated by a kinetic model, in which the rate of polymerization was fitted by a least-square optimization procedure and the molecular weight averages by the method of moments. The simulations of the coordination polymerization suggest the presence of two types of active sites, principally at low temperatures, and the reactivation of the deactivated sites via a boron-based activator. However, the effect of the temperature on the reactivation step was not clear; a deeper understanding via designed experiments is required.

show abstract

Polymerization of Ethylene with Zirconocene Heterogenized on Spherical ZSM-5

Cited by 3 publications

References 0 publications

Innovative route for the preparation of high-performance polyolefin materials based on unique dendrimeric silica particles

Innovative route for the preparation of high-performance polyolefin materials based on unique dendrimeric silica particles

Ethylene Polymerization via Zirconocene Catalysts and Organoboron Activators: An Experimental and Kinetic Modeling Study

Ethylene Polymerization via Zirconocene Catalysts and Organoboron Activators: An Experimental and Kinetic Modeling Study

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