Probing the coordinative unsaturation and local environment of Ti³âº sites in an activated high-yield Ziegler-Natta catalyst.
Angew Chem Int Ed Engl
; 54(16): 4857-60, 2015 Apr 13.
Article
en En
| MEDLINE
| ID: mdl-25706346
The typical activation of a fourth generation Ziegler-Natta catalyst TiCl4/MgCl2/phthalate with triethyl aluminum generates Ti(3+)â
centers that are investigated by multi-frequency continuous wave and pulse EPR methods. Two families of isolated, molecule-like Ti(3+)â
species have been identified. A comparison of the experimentally derived gâ
tensors and (35,37)Cl hyperfine and nuclear-quadrupole tensors with DFT-computed values suggests that the dominant EPR-active Ti(3+) â
species is located on MgCl2(110) surfaces (or equivalent MgCl2 terminations with tetra-coordinated Mg). O2 reactivity tests show that a fraction of these Tiâ
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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01-internacional
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MEDLINE
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En
Revista:
Angew Chem Int Ed Engl
Año:
2015
Tipo del documento:
Article
Pais de publicación:
Alemania