US EPA

6880757 

Journal Article 

Titanium-magnesium catalysts for olefin polymerization - effect of titanium oxidation state on catalyst performance 

Mikenas, TB; Tregubov, AA; Zakharov, VA; Echevskaya, LG; Matsko, MA; , 

2008 

1 

Polimery
ISSN: 0032-2725 

INDUSTRIAL CHEMISTRY RESEARCH INST 

WARSAW 

353-357 

WOS:000255499500003 

In this work, we investigated the influence of oxidation state of titanium and the effect of ethoxy groups' introduction into titanium compounds on the catalytic properties Of MgCl2 - supported catalysts [with triisobutylaluminum (TIBA) or triethylaluminum (TEA) as cocatalyst] in ethylene polymerization and ethylene 1-hexene copolymerization, and on the polymer characteristics. To prepare supported titanium-magnesium catalysts of various compositions, soluble compounds of titanium in different oxidation states [eta(6)-benzene-Ti2+Al2Cl8, Ti3+Cl3. nDBE, and Ti4+ (OEt)(2)Cl-2] were synthesized, analyzed by ESR and C-13 NMR methods, and immobilized on the highly dispersed magnesium chloride. The data were obtained on the effects produced by composition and oxidation state of titanium compounds (covering also commonly used TiCl4) on the activity, control of PE molecular weight by hydrogen, copolymerization ability, and molecular weight distribution (MWD) of polyethylene. The results obtained demonstrate that different titanium precursors comprising Ti(II), Ti(III) and Ti(IV) compounds supported on MgCl2 allow preparing the highly active catalysts for ethylene polymerization or ethylene/1-hexene copolymerization, It was found that titanium oxidation state in the initial titanium compounds had a weak effect on the molecular weight and MWD of PE, whereas the ligand environment of titanium affected this parameter more strongly.