One‐phase supported titanium‐based catalyst for polymerization of ethylene. IV. Effect of alkyl group at organoaluminium compound on catalyst performance

Šindelář, Pavel; Matula, Dalibor; Holeček, Jaroslav

doi:10.1002/(sici)1099-0518(199608)34:11<2163::aid-pola9>3.3.co;2-z

Cited by 2 publications

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“…[16][17][18][19][20][21] However, modern EPR techniques offer aw hole arsenal of specific experiments capable of investigating the local environment of paramagnetic species.H erein, we employ ac ombination of multi-frequencyC Wa nd pulse EPR experiments,c omplemented with DFT calculations,t oe lucidate the nature and reactivity of Ti 3+ centers generated by reacting af ourth generation MgCl 2 /TiCl 4 /dibutylphthalate precatalyst (Ti 2.0 %b yw eight and dibutylphthalate 8.9 %b yw eight) with TEA vapors. [16][17][18][19][20][21] However, modern EPR techniques offer aw hole arsenal of specific experiments capable of investigating the local environment of paramagnetic species.H erein, we employ ac ombination of multi-frequencyC Wa nd pulse EPR experiments,c omplemented with DFT calculations,t oe lucidate the nature and reactivity of Ti 3+ centers generated by reacting af ourth generation MgCl 2 /TiCl 4 /dibutylphthalate precatalyst (Ti 2.0 %b yw eight and dibutylphthalate 8.9 %b yw eight) with TEA vapors.…”

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Probing the Coordinative Unsaturation and Local Environment of Ti³⁺ Sites in an Activated High‐Yield Ziegler–Natta Catalyst

et al. 2015

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The typical activation of a fourth generation Ziegler-Natta catalyst TiCl4/MgCl2/phthalate with triethyl aluminum generates Ti(3+) centers that are investigated by multi-frequency continuous wave and pulse EPR methods. Two families of isolated, molecule-like Ti(3+) species have been identified. A comparison of the experimentally derived g tensors and (35,37)Cl hyperfine and nuclear-quadrupole tensors with DFT-computed values suggests that the dominant EPR-active Ti(3+) species is located on MgCl2(110) surfaces (or equivalent MgCl2 terminations with tetra-coordinated Mg). O2 reactivity tests show that a fraction of these Ti sites is chemically accessible, an important result in view of the search for the true catalyst active site in olefin polymerization.

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Probing the Coordinative Unsaturation and Local Environment of Ti³⁺ Sites in an Activated High‐Yield Ziegler–Natta Catalyst

et al. 2015

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“…Conventional X-band continuous wave (CW) EPR techniques have been used primarily to monitor and quantify the amount of reduced Ti species [7][8][9][10][11][12]. However, modern EPR techniques offer a whole arsenal of specific experiments capable of investigating the local coordination environment of Ti(III) species in ZN catalysts [13][14][15].…”

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Isolated Ti(III) Species on the Surface of a Pre-active Ziegler Natta Catalyst

et al. 2020

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The nature of Ti(III) species, introduced in working models of industrial Ziegler Natta catalyst precursors, consisting of MgCl2/TiCl4 binary systems, eventually containing different Lewis basis, are studied by a combination of X- and Q-band CW and pulse EPR spectroscopy. In Ziegler Natta catalysts, Ti(III) play the double role of active catalytic species and unconventional spin probes. On the binary system, two dominant Ti(III) species, characterized by distinctively different EPR spectra, are observed. 35,37Cl Q-Band HYSCORE spectra allow estimating the hyperfine and nuclear quadrupole interactions of directly coordinated Cl, characterized by a hyperfine dipolar contribution of the order of 5 MHz and nuclear quadrupole interactions of the order of e2qQ/h = 9 MHz. Interestingly, the two dominant EPR active species are selectively suppressed by the presence of different Lewis bases, indicating the possibility to address the long standing issue of the influence of Lewis bases in driving specific morphological configurations and influencing the catalytic properties of Ti(III) active sites.

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One‐phase supported titanium‐based catalyst for polymerization of ethylene. IV. Effect of alkyl group at organoaluminium compound on catalyst performance

Cited by 2 publications

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Probing the Coordinative Unsaturation and Local Environment of Ti³⁺ Sites in an Activated High‐Yield Ziegler–Natta Catalyst

Probing the Coordinative Unsaturation and Local Environment of Ti³⁺ Sites in an Activated High‐Yield Ziegler–Natta Catalyst

Isolated Ti(III) Species on the Surface of a Pre-active Ziegler Natta Catalyst

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One‐phase supported titanium‐based catalyst for polymerization of ethylene. IV. Effect of alkyl group at organoaluminium compound on catalyst performance

Cited by 2 publications

References 0 publications

Probing the Coordinative Unsaturation and Local Environment of Ti3+ Sites in an Activated High‐Yield Ziegler–Natta Catalyst

Probing the Coordinative Unsaturation and Local Environment of Ti3+ Sites in an Activated High‐Yield Ziegler–Natta Catalyst

Isolated Ti(III) Species on the Surface of a Pre-active Ziegler Natta Catalyst

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Probing the Coordinative Unsaturation and Local Environment of Ti³⁺ Sites in an Activated High‐Yield Ziegler–Natta Catalyst

Probing the Coordinative Unsaturation and Local Environment of Ti³⁺ Sites in an Activated High‐Yield Ziegler–Natta Catalyst