The influences of cocatalyst on propylene polymerization at high temperature with a MgCl2-supported TiCl4 catalyst system

Kojoh, Shin-ichi; Kioka, Mamoru; Kashiwa, Norio

doi:10.1016/s0014-3057(98)00155-4

Cited by 29 publications

(8 citation statements)

References 5 publications

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“…Up till now, several generations of heterogeneous Ziegler–Natta catalysts with very high isospecificity and activity have been successfully developed in the industrial circle for the synthesis of isotactic poly(propylene) (PP) through application of different electron donors including monoester, alkoxysilane, diester, and diether etc 2. However, the academic aspects regarding the real origin of the isospecificity of active sites and the stereospecific role of the electron donor in Ziegler–Natta catalysis are still open for discussion due to the complexities of these catalyst systems 3–9. Nowadays, it has been made clear that various factors besides the type of electron donor are also possibly making some contribution to the generation of isospecific active sites in heterogeneous Ziegler–Natta catalyst systems.…”

Section: Introductionmentioning

confidence: 99%

Stereospecific Nature of Active Sites on TiCl₄/MgCl₂ Ziegler–Natta Catalyst in the Presence of an Internal Electron Donor

Liu

Nitta

Nakatani

et al. 2003

Macro Chemistry & Physics

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Based on our previous study on the donor‐free TiCl4/MgCl2 catalyst, the stereospecific nature of active sites on this catalyst after the addition of an internal donor, ethylbenzoate (EB), was investigated by stopped‐flow propylene polymerization combined with temperature rising elution fractionation (TREF) and gel permeation chromatography (GPC) methods. The addition of donor EB was observed to significantly restrain the formation of aspecific sites (AS sites), to drastically promote formation of sites with the second highest isospecificity (IS2 sites) and to construct some new active sites with the highest isospecificity (IS3 sites). It was first observed that the formation of IS3 sites still strongly depends on the interaction between the catalyst and cocatalyst (up to 10 s of pretreatment) even in the presence of internal donor. Based on Busico and co‐workers' three sites model and our previous report, a plausible mechanism for the transformation of stereospecific active sites through some secondary bimetallic complexation reactions was proposed. The extraction of EB from the catalyst by the cocatalyst was found to initiate after 10 s of pretreatment resulting in partial transformation of IS3 sites into AS sites and IS1 sites.

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Section: Introductionmentioning

confidence: 99%

Stereospecific Nature of Active Sites on TiCl₄/MgCl₂ Ziegler–Natta Catalyst in the Presence of an Internal Electron Donor

Liu

Nitta

Nakatani

et al. 2003

Macro Chemistry & Physics

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“…In particular, the 2- i Bu system outperforms the 2-Et system that we previously reported (Table , entry 2) . This finding is in contrast to the work by Kojoh and co-workers, which showed an enhancement of activity with AlEt 3 over Al i Bu 3 (when incorporated as cocatalysts) for polymerization of propylene at temperatures of 50–100 °C …”

Section: Discussionmentioning

confidence: 99%

“…27 This finding is in contrast to the work by Kojoh and co-workers, which showed an enhancement of activity with AlEt 3 over AliBu 3 (when incorporated as cocatalysts) for polymerization of propylene at temperatures of 50−100 °C. 57 The results from the chemical and electrochemical studies described earlier in this report are reflected in the polymerization results, including some notable trends. First, regarding the appealing tunable MWD values, the AliBu 3 -based system is the champion, giving the largest MWD of any of the standard conditions tested.…”

Section: ■ Discussionmentioning

confidence: 99%

Heterobimetallic [Ti, Al] Complexes: Divergent Synthesis, Redox Properties, and Ethylene Polymerization Catalysis

et al. 2021

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Treatment of (Ind)(tBu 3 P = N)TiCl 2 (1; Ind = indenyl) with AlR 3 (R = Et, iBu, Me) affords heterobimetallic species of the form [(Ind)(tBu 3 PN)Ti(μ 2 -Cl) 2 AlR 2 ] (R = Et, 2-Et; iBu, 2-iBu; Me, 2-Me). The formation of these compounds occurs chemically or can be selectively triggered by electrochemical reduction of 1 in THF electrolyte solution containing AlR 3 . Cyclic voltammetry studies indicate that 1 undergoes one-electron reduction at ca. −2.0 V vs ferrocenium/ferrocene; in the presence of AlR 3 , reduction initiates coordination of [AlR 2 ] to the nascent [Ti III ] core and formation of 2-Me, 2-Et, and 2-iBu. Oxidation of these heterobimetallic species occurs at more positive potentials and leads to regeneration of 1. Single-crystal X-ray diffraction (XRD) analysis and magnetic resonance experiments confirm the formation of paramagnetic [Ti III , Al III ] species with each AlR 3 reagent. However, spectroscopic results and gas chromatography show that 2-Me is significantly less stable than 2-iBu and that 2-iBu is less stable than 2-Et. 2-Me, 2-Et, and 2-iBu are all active precatalysts for ethylene polymerization, but the diminished stability of 2-Me and 2-iBu in comparison with 2-Et is reflected in unique polymerization results in each case. 2-iBu produces polyethylene with a particularly broad molecular weight distribution (MWD), suggesting useful formation of multiple active species during catalysis. Conversely, 2-Me is a poor catalyst, suggesting detrimental speciation occurs with this system under the polymerization conditions.

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“…Zakharov [39] 在乙烯聚合中发现提高烷基铝浓度有利于向烷基铝链转移发生. Yoon等 [34] 和 Kashiwa等 [40] 发现随着烷基铝中R基团尺寸增加, 聚丙烯PP分子量和分布逐渐增加, 在高温(50∼100℃)聚合时PP分子量分布变窄.…”

Section: 吸附、络合在催化剂表面调控活性中心的立构规整unclassified

Progress on coordination polymerization mechanism of olefins catalyzed by heterogeneous TiCl<sub>4</sub>/MgCl<sub>2</sub> type Ziegler-Natta catalyst

Niu¹,

Wei²,

He³

2019

Sci. Sin.-Chim

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摘要非均相TiCl 4 /MgCl 2 型Ziegler-Natta催化剂(负载型Ziegler-Natta催化剂)因其高聚合活性、高立构选择性及低制备成本, 是目前聚烯烃领域重要的工业催化剂. 本文综述了负载型Ziegler-Natta催化剂催化α-烯烃(乙烯、丙烯)和共轭二烯烃(丁二烯、异戊二烯)配位聚合机理的研究进展, 包括TiCl 4 在MgCl 2 表面的吸附、钛的烷基化与还原、烷基铝的作用、活性中心数目、活性中心价态、活性中心模型、可能活性中心结构及催化机理、给电子体作用等. 最后, 展望了负载型Ziegler-Natta催化剂催化烯烃聚合的机遇与挑战. 关键词非均相, 负载型Ziegler-Natta催化剂, α-烯烃, 共轭二烯烃, 聚合机理 2 α-烯烃配位聚合机理 2.1 TiCl 4 在MgCl 2 表面的结构作为负载型Ziegler-Natta催化剂的载体, MgCl 2 主引用格式: Niu Q, Peng W, He A. Developments in coordination polymerization mechanism of olefins catalyzed by heterogeneous TiCl 4 /MgCl 2 type Ziegler-Natta catalyst.

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The influences of cocatalyst on propylene polymerization at high temperature with a MgCl2-supported TiCl4 catalyst system

Cited by 29 publications

References 5 publications

Stereospecific Nature of Active Sites on TiCl₄/MgCl₂ Ziegler–Natta Catalyst in the Presence of an Internal Electron Donor

Stereospecific Nature of Active Sites on TiCl₄/MgCl₂ Ziegler–Natta Catalyst in the Presence of an Internal Electron Donor

Heterobimetallic [Ti, Al] Complexes: Divergent Synthesis, Redox Properties, and Ethylene Polymerization Catalysis

Progress on coordination polymerization mechanism of olefins catalyzed by heterogeneous TiCl<sub>4</sub>/MgCl<sub>2</sub> type Ziegler-Natta catalyst

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The influences of cocatalyst on propylene polymerization at high temperature with a MgCl2-supported TiCl4 catalyst system

Cited by 29 publications

References 5 publications

Stereospecific Nature of Active Sites on TiCl4/MgCl2 Ziegler–Natta Catalyst in the Presence of an Internal Electron Donor

Stereospecific Nature of Active Sites on TiCl4/MgCl2 Ziegler–Natta Catalyst in the Presence of an Internal Electron Donor

Heterobimetallic [Ti, Al] Complexes: Divergent Synthesis, Redox Properties, and Ethylene Polymerization Catalysis

Progress on coordination polymerization mechanism of olefins catalyzed by heterogeneous TiCl&lt;sub&gt;4&lt;/sub&gt;/MgCl&lt;sub&gt;2&lt;/sub&gt; type Ziegler-Natta catalyst

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Stereospecific Nature of Active Sites on TiCl₄/MgCl₂ Ziegler–Natta Catalyst in the Presence of an Internal Electron Donor

Stereospecific Nature of Active Sites on TiCl₄/MgCl₂ Ziegler–Natta Catalyst in the Presence of an Internal Electron Donor

Progress on coordination polymerization mechanism of olefins catalyzed by heterogeneous TiCl<sub>4</sub>/MgCl<sub>2</sub> type Ziegler-Natta catalyst