Kinetic Features of Ethylene Polymerization over Supported Catalysts [2,6-Bis(imino)pyridyl Iron
Dichloride/Magnesium Dichloride] with AlR3 as an Activator
Journal of Polymer Science, Part A: Polymer Chemistry
, E-ISSN: 1099-0518
||Hydrogen activation, Iron (II) complex, Kinetics (polym.), MgCl2 supported catalysts, Molecular weight distribution/molar mass distribution, Polyethyle (PE)
Mikenas Tatiana B.
Zakharov Vladimir A.
Echevskaya Lyudmila G.
Matsko Mikhail A.
Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Science, Prospekt Akademika Lavrentieva 5, Novosibirsk 630090, Russia
The effects of polymerization temperature, polymerization time, ethylene and hydrogen concentration, and effect of comonomers (hexene-1, propylene) on the activity of supported catalyst of composition LFeCl2/MgCl2-Al(i-Bu)3 (L = 2,6-bis[1-(2,6-dimethylphenylimino)ethyl] pyridyl) and polymer characteristics (molecular weight (MW), molecular-weight distribution (MWD), molecular structure) have been studied. Effective activation energy of ethylene polymerization over LFeCl2/MgCl2-Al(i-Bu)3 has a value typical of supported Ziegler–Natta catalysts (11.9 kcal/mol). The polymerization reaction is of the first order with respect to monomer at the ethylene concentration >0.2 mol/L. Addition of small amounts of hydrogen (9–17%) significantly increases the activity; however, further increase in hydrogen concentration decreases the activity. The IRS and DSC analysis of PE indicates that catalyst LFeCl2/MgCl2-Al(i-Bu)3 has a very low copolymerizing ability toward propylene and hexene-1. MW and MWD of PE produced over these catalysts depend on the polymerization time, ethylene and hexene-1 concentration. The activation effect of hydrogen and other kinetic features of ethylene polymerization over supported catalysts based on the Fe (II) complexes are discussed.