Macromol. React. Eng. 12/2013

Zeng, Yanning; Matta, Akanksha; Dwivedi, Sumant; Taniike, Toshiaki; Terano, Minoru

doi:10.1002/mren.201370037

Cited by 3 publications

(4 citation statements)

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“…The samples were prepared by dissolving 240 mg of PE in 3.0 mL of 1,2,4‐trichlorobenzene and benzene‐d 6 (4:1 v/v). The contents of methyl branches and ≥hexyl branches were decided according to previously proposed methods . Gel permeation chromatography (GPC, Waters Alliance GPCV2000CV) with polystyrene gel columns (Shodex UT‐806 M) was used to analyze MWD of the produced PE using 1,2,4‐trichlorobenzene as eluent at 140 °C.…”

Section: Methodsmentioning

confidence: 99%

Activation and Deactivation of Phillips Catalyst for Ethylene Polymerization Using Various Activators

Zeng

Chammingkwan

Baba

et al. 2016

Macro Reaction Engineering

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The present article reveals important roles of metal alkyl activators in tuning the performance of the Phillips catalyst in ethylene polymerization. The addition of aluminum alkyl aids the activation of the catalyst, while excess addition leads to the loss of the activity. The balance between the activation and deactivation depends on the type of employed aluminum alkyl, and tri‐n‐octylaluminum offers the most efficient catalyst usage by preferentially suppressing the deactivation. The passivation of aluminum trialkyl with a hindered phenol mildens not only the deactivation but also chain transfer reactions, leading to an increment of high molecular weight fractions.

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Section: Methodsmentioning

confidence: 99%

Activation and Deactivation of Phillips Catalyst for Ethylene Polymerization Using Various Activators

Zeng

Chammingkwan

Baba

et al. 2016

Macro Reaction Engineering

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“…[14][15][16] A few studies concerning the combination of chromium-based with nonchromium based catalysts were also published. [17][18][19][20][21][22] Following this trend, a novel SiO 2 -supported Cr-V bimetallic catalyst was prepared by using the residual surface hydroxyl groups in a SiO 2 -supported vanadium catalyst to support bis(triphenysilyl) chromate in our previous work. [23] Compared with the silyl-chromate (S-2) catalyst which is synthesized by supporting bis(triphenysilyl) chromate separately on silica, the resulting PE made by the Cr-V bimetallic catalyst showed higher molecular weight (MW) and bimodal MWD, while ethylene/1-hexene copolymers also exhibited a better short-chain branch distribution (SCBD).…”

Section: Doi: 101002/mren201700059mentioning

confidence: 99%

“…Extensive research in this area deal with the immobilization of two or more single‐site catalysts on the same support and also there are some examples about hybrid or mixed Ziegler–Natta/metallocene catalysts . A few studies concerning the combination of chromium‐based with nonchromium based catalysts were also published . Following this trend, a novel SiO 2 ‐supported Cr‐V bimetallic catalyst was prepared by using the residual surface hydroxyl groups in a SiO 2 ‐supported vanadium catalyst to support bis(triphenysilyl) chromate in our previous work .…”

Section: Introductionmentioning

confidence: 99%

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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“…[ 32–36 ] In addition, there were a few reports on Ziegler–Natta/metallocene hybrid catalysts [ 37–39 ] and the combination of chromium based catalyst with other nonchromium based catalysts. [ 40–43 ] Our group researched several catalyst systems for bimodal PE with great processability and mechanical properties. [ 44–46 ] However, the detrimental interaction among different metallic species needed to be considered because the catalysts to produce UHMWPE were sensitive to other metal.…”

Section: Introductionmentioning

confidence: 99%

Novel SiO₂‐Supported Chromium Oxide/Chromocene Dual Site Catalysts for Synthesis of Bimodal UHMWPE/HDPE in Reactor Alloys

Wang

Jin

Liu

et al. 2020

Macro Chemistry & Physics

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Polyethylene (PE) with bimodal molecular weight distribution (MWD) has drawn attention from both academia and industry. Bimodal PE combines great processability with outstanding mechanical properties. The single‐reactor technology process through a dual site catalyst system is an optimal strategy considering the economic effect and the manufacturing technique. To satisfy the demand of the dual site catalyst system for producing bimodal PE, novel SiO2‐supported chromium oxide/chromocene dual site catalysts for ethylene polymerization are successfully synthesized and systematically investigated. The novel catalysts are prepared by using the residual hydroxyl groups on the surface of SiO2‐supported chromium oxide (CrOx) Phillips catalyst to introduce chromocene. It is found that the novel dual site catalysts combine the advantages of chromocene catalyst (S‐9 catalyst) and Phillips CrOx/SiO2 catalyst. The activities of the dual site catalysts are doubled at least compared to the S‐9 catalyst due to the high activity of the CrOx active center. The products of the dual site catalysts show significantly high molecular weight (MW) with bimodal MWD through ultrahigh molecular weight polyethylene/high‐density polyethylene in reactor alloys. The dual site catalysts show great hydrogen response according to the hydrogen experiment results, which lead to the easy control of MW.

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Macromol. React. Eng. 12/2013

Cited by 3 publications

References 0 publications

Activation and Deactivation of Phillips Catalyst for Ethylene Polymerization Using Various Activators

Activation and Deactivation of Phillips Catalyst for Ethylene Polymerization Using Various Activators

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

Novel SiO₂‐Supported Chromium Oxide/Chromocene Dual Site Catalysts for Synthesis of Bimodal UHMWPE/HDPE in Reactor Alloys

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Macromol. React. Eng. 12/2013

Cited by 3 publications

References 0 publications

Activation and Deactivation of Phillips Catalyst for Ethylene Polymerization Using Various Activators

Activation and Deactivation of Phillips Catalyst for Ethylene Polymerization Using Various Activators

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

Novel SiO2‐Supported Chromium Oxide/Chromocene Dual Site Catalysts for Synthesis of Bimodal UHMWPE/HDPE in Reactor Alloys

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Product

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About

Novel SiO₂‐Supported Chromium Oxide/Chromocene Dual Site Catalysts for Synthesis of Bimodal UHMWPE/HDPE in Reactor Alloys