Toward an Understanding of the Molecular Level Properties of Ziegler−Natta Catalyst Support with and without the Internal Electron Donor

2010 ◽  
Vol 115 (5) ◽  
pp. 1952-1960 ◽  
Author(s):  
K. S. Thushara ◽  
Edwin S. Gnanakumar ◽  
Renny Mathew ◽  
Ratnesh K. Jha ◽  
T. G. Ajithkumar ◽  
...  
Keyword(s):  
Electron Donor ◽  
Molecular Level ◽  
Catalyst Support ◽  
Natta Catalyst ◽  
Internal Electron ◽  
Ziegler Natta Catalyst

scholarly journals Comparative Study on Kinetics of Ethylene and Propylene Polymerizations with Supported Ziegler–Natta Catalyst: Catalyst Fragmentation Promoted by Polymer Crystalline Lamellae

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 358 ◽  
Author(s):  
Zhen Zhang ◽  
Baiyu Jiang ◽  
Feng He ◽  
Zhisheng Fu ◽  
Junting Xu ◽  
...  
Keyword(s):  
Propylene Polymerization ◽  
Lamellar Thickness ◽  
Efficient Catalyst ◽  
Two Systems ◽  
Key Factor ◽  
Natta Catalyst ◽  
Internal Electron ◽  
20 Nm ◽  
Kinetics Of ◽  
Ziegler Natta Catalyst

The kinetic behaviors of ethylene and propylene polymerizations with the same MgCl2-supported Ziegler–Natta (Z–N) catalyst containing an internal electron donor were compared. Changes of polymerization activity and active center concentration ([C*]) with time in the first 10 min were determined. Activity of ethylene polymerization was only 25% of that of propylene, and the polymerization rate (Rp) quickly decayed with time (tp) in the former system, in contrast to stable Rp in the latter. The ethylene system showed a very low [C*]/[Ti] ratio (<0.6%), in contrast to a much higher [C*]/[Ti] ratio (1.5%–4.9%) in propylene polymerization. The two systems showed noticeably different morphologies of the nascent polymer/catalyst particles, with the PP/catalyst particles being more compact and homogeneous than the PE/catalyst particles. The different kinetic behaviors of the two systems were explained by faster and more sufficient catalyst fragmentation in propylene polymerization than the ethylene system. The smaller lamellar thickness (<20 nm) in nascent polypropylene compared with the size of nanopores (15–25 nm) in the catalyst was considered the key factor for efficient catalyst fragmentation in propylene polymerization, as the PP lamellae may grow inside the nanopores and break up the catalyst particles.

Modeling the Stabilization of Surface Defects by Donors in Ziegler–Natta Catalyst Support

2014 ◽  
Vol 118 (9) ◽  
pp. 4791-4796 ◽  
Author(s):  
Andrey Bazhenov ◽  
Mikko Linnolahti ◽  
Tapani A. Pakkanen ◽  
Peter Denifl ◽  
Timo Leinonen
Keyword(s):  
Surface Defects ◽  
Catalyst Support ◽  
Natta Catalyst ◽  
Ziegler Natta Catalyst
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