Precise arguments on the distribution of stereospecific active sites on MgCl2-supported ziegler-natta catalysts

2004 ◽  
Vol 213 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Boping Liu ◽  
Takashi Nitta ◽  
Hisayuki Nakatani ◽  
Minoru Terano
Keyword(s):  
Active Sites ◽  
Ziegler Natta Catalysts

Energy Distribution of Active Sites in Heterogeneous Ziegler-Natta Catalysts. Method of Study of Active Site Non-Uniformity

1999 ◽  
pp. 89-96 ◽  
Author(s):  
L. A. Novokshonova ◽  
N. Yu Kovaleva ◽  
Yu A. Gavrilov ◽  
V. G. Krasheninnikov ◽  
T. A. Ladygin ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Active Site ◽  
Active Sites ◽  
Ziegler Natta Catalysts

Study of energy distribution of active sites in heterogeneous Ziegler-Natta catalysts

1997 ◽  
Vol 39 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Lyudmila A. Novokshonova ◽  
Natalia Yu. Kovaleva ◽  
Yurii A. Gavrilov ◽  
Vadim G. Krasheninnikov ◽  
Ilia O. Leipunskii ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Active Sites ◽  
Ziegler Natta Catalysts

New Evidence on the Nature of the Active Sites in Heterogeneous Ziegler−Natta Catalysts for Propene Polymerization

1997 ◽  
Vol 30 (16) ◽  
pp. 4786-4790 ◽  
Author(s):  
Vincenzo Busico ◽  
Roberta Cipullo ◽  
Giovanni Talarico ◽  
Anna Laura Segre ◽  
John C. Chadwick
Keyword(s):  
Active Sites ◽  
Propene Polymerization ◽  
New Evidence ◽  
Ziegler Natta Catalysts

scholarly journals Spectroscopic Signature and Structure of Active Centers in Ziegler-Natta Polymerization Catalysts revealed by Electron Paramagnetic Resonance

2020 ◽  
Author(s):  
Anton Ashuiev ◽  
mathieu humber ◽  
sebastien norsic ◽  
jean blahut ◽  
david gajan ◽  
...  
Keyword(s):  
Active Sites ◽  
Atomic Scale ◽  
Paramagnetic Species ◽  
Polymerization Catalysts ◽  
Active Centers ◽  
Paramagnetic Resonance ◽  
Joint Application ◽  
Spectroscopic Signatures ◽  
Electron Paramagnetic ◽  
Ziegler Natta Catalysts

Despite decades of extensive studies, the atomic-scale structure of active sites in heterogeneous Ziegler-Natta (ZN) catalysts remains elusive and a matter of debate. Here, the structure of polymerization ZN catalysts is elucidated from magnetic resonance experiments carried out on samples reacted with increasing amounts of BCl<sub>3</sub> so as to enhance the concentration of active sites and observe clear spectroscopic signatures. Notably, we show that EPR and NMR spectroscopy of the activated ZN catalysts enables to observe paramagnetic species whose amount increases in conjunction with the catalytic activity. The joint application of 2D HYSCORE experiments and DFT calculations reveals the presence of bimetallic alkyl-Ti(III),Al complexes that are assigned to the catalytic centers of MgCl<sub>2</sub>-supported Ziegler-Natta catalysts

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