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

ELENA MORRA, Elio GIAMELLO, Sabine Van Doorslaer, Giuseppe Antinucci, MADDALENA D'AMORE, Vincenzo Busico, Mario CHIESA

Risultato della ricerca: Contributo su rivistaArticolo in rivistapeer review

Abstract

The typical activation of a fourth generation Ziegler-Natta catalyst TiCl4/MgCl2/phthalate with triethyl aluminum generates Ti3+ centers that are investigated by multi-frequency continuous wave and pulse EPR methods. Two families of isolated, molecule-like Ti3+ species have been identified. A comparison of the experimentally derived g tensors and 35,37Cl hyperfine and nuclear-quadrupole tensors with DFT-computed values suggests that the dominant EPR-active Ti3+ 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.
Lingua originaleInglese
pagine (da-a)4857-4860
Numero di pagine4
RivistaAngewandte Chemie - International Edition
Volume54
Numero di pubblicazione16
DOI
Stato di pubblicazionePubblicato - 2015

Keywords

  • EPR spectroscopy
  • Heterogeneous catalysis
  • Polymerization
  • Titanium
  • Ziegler-Natta catalysts
  • Chemistry (all)
  • Catalysis

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