Effect of internal lewis base on active site distribution for ethylene/1-octene copolymerization by TiCl4/lewis base/MgCl2 catalysts

Wang, Luhai; Yang, Min; Ren, Hegang; Liu, Binyuan; Yan, Weidong; Kim, Il

doi:10.1007/s13233-009-0126-8

Cited by 5 publications

(2 citation statements)

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“…This approach has been used to understand the distribution of active site types in Ziegler–Natta catalysts for propylene polymerization as a function of polymerization temperature and time, type of cocatalyst and electron donor, copolymerizations with other α‐olefins, and catalyst synthesis conditions. [ 51–66 ] Similar deconvolution studies were used to understand the effect of polymerization conditions and catalyst formulations for the polymerization of ethylene and α‐olefins with Ziegler–Natta [ 67–81 ] and Phillips/chromium catalysts. [ 82–84 ] Other studies used MWD deconvolution to identify active site populations for the polymerization of 1‐octene, [ 85 ] 1‐hexene, [ 86–89 ] and 1‐butene [ 90,91 ] with Ziegler–Natta catalysts.…”

Section: Looking Back At the Literaturementioning

confidence: 99%

Polyolefin microstructural deconvolution methods: The good, the bad, and the ugly

Soares

2023

Can J Chem Eng

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The deconvolution of the molecular weight distribution (MWD) of polyolefins into Schultz–Flory most probable distributions has become the standard method to identify the number of site types on multiple‐site‐type olefin polymerization catalysts such as Ziegler–Natta, Phillips, and some supported metallocenes. This method has been used to quantify the effect of polymerization conditions and catalyst formulations on polyolefin MWD and olefin polymerization kinetics. Related methods have also been developed to deconvolute other polyolefin microstructure features, such as the chemical composition and comonomer sequence length distributions. In this paper, I explain the premises behind these deconvolution models and review the publications in this area, highlighting the advantages, disadvantages, and misuses of these methods. I also propose a revised formulation on how to model the MWD of polyolefins made with multiple‐site‐type catalysts using ratio distributions for propagation and chain transfer frequencies. The main objective of this overview article is to highlight the strengths, but also show the pitfalls, of polyolefin microstructure deconvolution methods.

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Section: Looking Back At the Literaturementioning

confidence: 99%

Polyolefin microstructural deconvolution methods: The good, the bad, and the ugly

Soares

2023

Can J Chem Eng

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“…29,30 Thus, the nature of the catalysts (type of catalyst, and presence of supports or cocatalysts) have a profound influence on the resulting microstructure and therefore on the final properties. 31,32 Moreover, due to the strong dependence of the polymer properties on the comonomer ratio, it is necessary to keep constant the reaction conditions over the entire polymerization period, 33 and therefore, the control of the feed monomer ratio is essential to obtain a copolymer in a semi-batch reactor.…”

Section: Introductionmentioning

confidence: 99%

Characterization and properties of ethylene-propylene copolymers synthesized with homogeneous and supported metallocene catalyst in the whole range of compositions

et al. 2011

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Two series of ethylene-propylene copolymers were synthesized in the whole composition range using a metallocene catalyst, one in the homogeneous phase (H copolymers), and the other with the catalyst supported in silica (S copolymers). Some differences were found between the two groups. Therefore, the amount of ethylene needed to obtain a certain proportion of the γ form is lower in the H than in S series. Moreover, the composition to obtain the pseudo hexagonal form is also different for the two groups. On the other hand, degree of crystallinity, crystal sizes and microhardness values display a similar variations with the comonomer content of the two series. Consequently, from a macroscopic point of view, materials with similar macroscopic mechanical properties can be produced using both supported and homogeneous metallocene catalysts despite the structural differences.

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Effects of Internal Electron Donor on Distribution and Reactivity of Active Centers in Ethylene/1‐Hexene Copolymerization with MgCl₂‐Supported Ziegler‐Natta Catalyst

Tao

Fan

2023

Macro Reaction Engineering

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Ethylene/1‐hexene copolymerization with two MgCl2‐supported Ziegler‐Natta catalysts containing no internal electron donor or diethylphthalate (DEP) is conducted for different polymerization time . Effects of DEP on active center distribution are studied by fractionating each copolymer sample into boiling n‐heptane soluble (C7‐sol) and insoluble (C7‐ins) fractions, and counting the number of active centers in the copolymer fractions . The main effect of introducing DEP in the catalyst are reduction in the Ti content and significant increase in the proportion of active centers producing C7‐ins fraction. The propagation rate constants of ethylene insertion (kpE) and 1‐hexene insertion (kpH) are respectively estimated by linear fitting/extrapolating the change of apparent propagation rate constants (kpi)a with polymer yield according to a simplified multi‐grain particle model. In both catalysts, kpE in the C7‐ins fraction is 9–12 times larger than that in the C7‐sol fraction, and kpH in the C7‐ins fraction is 3–4 times larger than that in the C7‐sol fraction. The two groups of active centers have distinctly different catalytic properties. Introducing DEP reduced the kpE and kpH values and the extent of diffusion limitation . In summary, addition of electron donor in MgCl2‐supported Z‐N catalyst significantly changed the active center distribution and catalytic properties of its two groups of active centers.

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Effect of internal lewis base on active site distribution for ethylene/1-octene copolymerization by TiCl4/lewis base/MgCl2 catalysts

Cited by 5 publications

References 20 publications

Polyolefin microstructural deconvolution methods: The good, the bad, and the ugly

Polyolefin microstructural deconvolution methods: The good, the bad, and the ugly

Characterization and properties of ethylene-propylene copolymers synthesized with homogeneous and supported metallocene catalyst in the whole range of compositions

Effects of Internal Electron Donor on Distribution and Reactivity of Active Centers in Ethylene/1‐Hexene Copolymerization with MgCl₂‐Supported Ziegler‐Natta Catalyst

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Effect of internal lewis base on active site distribution for ethylene/1-octene copolymerization by TiCl4/lewis base/MgCl2 catalysts

Cited by 5 publications

References 20 publications

Polyolefin microstructural deconvolution methods: The good, the bad, and the ugly

Polyolefin microstructural deconvolution methods: The good, the bad, and the ugly

Characterization and properties of ethylene-propylene copolymers synthesized with homogeneous and supported metallocene catalyst in the whole range of compositions

Effects of Internal Electron Donor on Distribution and Reactivity of Active Centers in Ethylene/1‐Hexene Copolymerization with MgCl2‐Supported Ziegler‐Natta Catalyst

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Effects of Internal Electron Donor on Distribution and Reactivity of Active Centers in Ethylene/1‐Hexene Copolymerization with MgCl₂‐Supported Ziegler‐Natta Catalyst