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 originale | Inglese |
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pagine (da-a) | 4857-4860 |
Numero di pagine | 4 |
Rivista | Angewandte Chemie - International Edition |
Volume | 54 |
Numero di pubblicazione | 16 |
DOI | |
Stato di pubblicazione | Pubblicato - 2015 |
Keywords
- EPR spectroscopy
- Heterogeneous catalysis
- Polymerization
- Titanium
- Ziegler-Natta catalysts
- Chemistry (all)
- Catalysis