Active centers in Ziegler–Natta catalysts: Formation kinetics and structure

Kissin, Yury V.

doi:10.1016/j.jcat.2012.05.012

Cited by 55 publications

(48 citation statements)

References 61 publications

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“…Nor is there any sign of a Cl 3 Ti-OR compound, which should, according to the model compound 1206-2, exhibit a strong absorption peak at 1073 cm −1 . This suggests that there is no significant shift of -OR groups from the EtAl(OR) 2 compound to TiCl 4 . The fact that most or all of the titanium was in the form of TiCl 4 in this catalyst, and thereby outside the range of the measuring instrument, can explain why no titanium could be detected in the IR-spectra of the catalysts even if the catalyst contained 4 w% of titanium.…”

Section: Ir Results For the Catalystmentioning

confidence: 98%

“…Generally only two of the chlorine atoms of TiCl 4 tended to react, even in the presence of excess alcohol. Hence, the results indicated that an Al-Et group reacted more readily with alcohol than a Ti-Cl group in TiCl 4 .…”

Section: Ir Absorption Bands In the Model Compoundsmentioning

confidence: 91%

“…These catalysts produce a polymer material with a rather broad molecular weight distribution indicating that the catalysts have a structure of at least five different types of active sites [4][5][6]. The main components of these catalysts are: MgCl 2 as support material, TiCl 4 as the active transition metal, and triethylaluminum (AlEt 3 , TEA) as cocatalyst. The MgCl 2 support material must be in a disordered, amorphous crystal state to enable the TiCl 4 to link via coordination bonds to the edges of the MgCl 2 crystal plates and thereby create active polymerization centers.…”

Section: Introductionmentioning

confidence: 99%

“…The main components of these catalysts are: MgCl 2 as support material, TiCl 4 as the active transition metal, and triethylaluminum (AlEt 3 , TEA) as cocatalyst. The MgCl 2 support material must be in a disordered, amorphous crystal state to enable the TiCl 4 to link via coordination bonds to the edges of the MgCl 2 crystal plates and thereby create active polymerization centers. The amorphous structure of the MgCl 2 support material is created by chemical activation in the course of catalyst synthesis.…”

Section: Introductionmentioning

confidence: 99%

“…Several compounds were synthesized for comparison and to aid interpretation of the infrared (IR) spectra. The catalysts were prepared by precipitating MgCl 2 , which was used as support material and subsequently treated with TiCl 4 . The thickness of the catalyst crystals was calculated from the XRD reflection at 2θ = 50°.…”

Section: Introductionmentioning

confidence: 99%

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Heterogeneous Ziegler–Natta catalysts with various sizes of MgCl2 crystallites: synthesis and characterization

et al. 2016

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Section: Ir Results For the Catalystmentioning

confidence: 98%

Section: Ir Absorption Bands In the Model Compoundsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Heterogeneous Ziegler–Natta catalysts with various sizes of MgCl2 crystallites: synthesis and characterization

et al. 2016

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Ziegler–Natta Catalysts

Fan

2018

Encyclopedia of Polymer Science and Technology

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First invented in 1953, Ziegler–Natta catalysts have been used widely in the industrial production of polyolefins and other important polymers since the 1960s. In recent years, polymers synthesized with these catalysts account for more than 30% of the total production of polymers. This article briefly introduces the history and main developments of Ziegler–Natta catalysts and explains their preparation, composition, and mechanism of the catalysis process. Particular emphasis is put on the currently more important MgCl 2 ‐supported Ziegler–Natta catalysts. Main features of the olefin polymerization with MgCl 2 ‐supported Ziegler–Natta catalysts are presented, including the formation and structure of active sites, main reactions with the active sites, origin of stereospecificity, reaction kinetics, and morphology of the nascent polymer particles. The main olefin polymerization processes with these catalysts are also briefly discussed.

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