Silica‐Supported Silyl Chromate–Based Ethylene Polymerization Catalysts

Cann, Kevin

doi:10.1002/9780470504437.ch11

Cited by 3 publications

(2 citation statements)

References 10 publications

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“…Here, slurry and solution processes are used that operate at 85-100 C and 1-3 MPa, and 130-200 C and ≤10 MPa, respectively. [1][2][3][4][5] The α-olefin incorporation level greatly influences the resulting crystalline versus amorphous phase morphology. A significant degree of comonomer incorporation transforms the lamellar crystalline region to an almost amorphous fringed micelle region 6 and makes the target elastomer.…”

Section: Introductionmentioning

confidence: 99%

“…Organometallic precatalysts, in the presence of a cocatalyst namely memethylaluminoxane (MAO), copolymerize ethylene with an α ‐olefin comonomer such as 1‐hexene, 1‐octene, 1‐decene, and so on. Here, slurry and solution processes are used that operate at 85–100°C and 1–3 MPa, and 130–200°C and ≤10 MPa, respectively 1–5 . The α ‐olefin incorporation level greatly influences the resulting crystalline versus amorphous phase morphology.…”

Section: Introductionmentioning

confidence: 99%

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Catalytic making of ethylene‐1‐hexene elastomers: Thermodynamic guide to process development

Atiqullah,

Abdelaal,

Adamu

et al. 2023

AIChE Journal

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Ethylene‐alpha olefin elastomers have versatile applications. Solution copolymerization makes them, using ethylene and alpha olefin‐rich comonomer feed and metallocene and postmetallocene precatalysts, at laboratory and industry conditions. Hence, this study models ethylene solubility in toluene‐1‐hexene and n‐hexane‐1‐hexene mixtures using VLE criterion, Peng–Robinson EoS, vdW1f mixing rule, and Shulgin's activity coefficient‐Henry's constant formalism. Levenberg–Marquardt algorithm, with initial conditions comprising quasi‐ideal K factor correlation and Tait liquid phase EoS, solved the model equations. This eliminates present cumbersome literature approach. The predicted solubilities well match the experimental values at all temperature and pressure. Ethylene solubility correlates the liquid phase fluid compressibility to the corresponding catalyst active center residential environment. This offers a new approach to investigate catalyst and copolymerization phenomena and develop ethylene‐1‐hexene elastomer process. Evaluating copolymerization and microstructural property, using ethylene solubility ignoring that in 1‐hexene, introduces significant errors. The present work corrects them and solves a long‐standing polymer reaction engineering problem.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Catalytic making of ethylene‐1‐hexene elastomers: Thermodynamic guide to process development

Atiqullah,

Abdelaal,

Adamu

et al. 2023

AIChE Journal

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Effect of Alkyl Aluminums on Ethylene Polymerization Reactions with a Cr‐V Bimetallic Catalyst

Bao

Tian

Jin

et al. 2018

Macro Reaction Engineering

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The effect of introducing various types of alkyl aluminums directly into the catalyst and/or in the polymerization process as cocatalyst on the efficiency of a Cr‐V bimetallic catalyst for ethylene polymerization is systematically investigated. Results indicate that polymerization activity, kinetic behavior, and polymer properties of the Cr‐V catalyst are strongly affected by using alkyl aluminums in different stages of polymerization, due to the different responses and sensitivities of the two metal centers to alkyl aluminum. When employed as cocatalyst, triisobutyl aluminum gives high activity and polyethylene with relatively low molecular weight, while diethylaluminum chloride cocatalyzes the production of ultra‐high molecular weight polyethylene but with very low activity. On the other hand, the pre‐reduction of the bimetallic catalyst by alkyl aluminums has a marked promotion effect on catalyst efficiency. It is suggested that the addition of alkyl aluminum to the catalyst and to the reactor as cocatalyst are more or less equivalent in their effects on the improvement of polymerization activity, but they behave in different ways to affect polymer properties.

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One pot synthesis of bimodal UHMWPE/HDPE in‐reactor blends with Cr/V bimetallic catalysts

Jin

Zhao

Cheng

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

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Bimodal ultra‐high‐molecular‐weight polyethylene (UHMWPE)/high‐density polyethylene (HDPE) in‐reactor blends (IRBs) are produced by the bimetallic catalysts, which are synthesized through co‐supporting silylchromate and vanadium‐oxide‐based catalysts on silica or alumina, zirconia and titania‐modified silica. After support modification, the activities of the catalysts for ethylene polymerization are substantially enhanced. The IRBs produced by the modified catalysts also contain more UHMWPE and low‐molecular‐weight polyethylene (LMWPE) fractions, and have much broader molecular weight distribution (MWD). The homogeneous nature of the IRBs is preliminarily confirmed by the differential scanning calorimetry melting curves, showing unique melting peak in both nascent and recrystallized states. The rheological results reflect that the viscosity of the IRBs is reduced more or less when compared with UHMWPE. The distinct elastic dominance of the IRBs is also observed, implying the UHMWPE characteristics in the IRBs. In addition, the intimate mixing of the IRBs is further verified by the similar slopes of Han curves for the polyethylene (PE) samples. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3404–3412

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Silica‐Supported Silyl Chromate–Based Ethylene Polymerization Catalysts

Cited by 3 publications

References 10 publications

Catalytic making of ethylene‐1‐hexene elastomers: Thermodynamic guide to process development

Catalytic making of ethylene‐1‐hexene elastomers: Thermodynamic guide to process development

Effect of Alkyl Aluminums on Ethylene Polymerization Reactions with a Cr‐V Bimetallic Catalyst

One pot synthesis of bimodal UHMWPE/HDPE in‐reactor blends with Cr/V bimetallic catalysts

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