Titanium-magnesium catalysts for ethylene polymerization.
The effect of the Lewis base in [MgCl2(LB)2] on catalyst activity
Polimery 1997, No 10, 604
Titanium-magnesium catalysts containing Lewis bases are very effective in the polymerization of ethylene and a-olefins. Lewis bases either influence the catalytic properties directly or change the structure of the catalyst. The catalysts under study were obtained from titanium (IV) and titanium (III) chlorides supported on complexes of magnesium dichloride with Lewis bases, of the type [MgCl2(LB)2], where LB: ethanol, n-pentanol, tetrahydrofuran, ethyl acetate, ethyl propionate, or ethyl benzoate. Thecatalysts were activated with organoaluminum compounds. Activity of the catalyst system varies with the organoaluminum compound used. The nature of the Lewis base in the solid magnesium dichloride complex affects the performance of the catalyst system. Most active catalysts were obtained from the complexes containing the Lewis bases of high donor numbers (e.g. ethanol, tetrahydrofuran). Not only the ethylene polymerization but also the properties of polyethylene were found to be affected by Lewis bases.