| Popis: |
A new type of Ziegler ethylene polymerization catalyst has been formed using as a support, siloxene, a layer compound with an empirical formula of Si2H2O. Siloxene is a reducing compound, and it reacts with excess TiCl4, giving an inactive brown solid with 5.2% Ti and 8.0% Cl. However, when additional TiCl4 is reduced by a metal alkyl and precipitated onto the brown solid, a catalyst with moderate activity is formed. Maximum activity for ethylene polymerization was obtained when the catalyst was pretreated with n-butylmagnesium. contained 0.06 g CaCl2/g siloxene, and was run at 80°C with 40-50 ppm of TEA cocatalyst. These catalysts are very active in the initial portion of the reaction, but the activity decreases rapidly over the first 30 min. Their hydrogen response and hexene incorporation is similar to that observed with other Ziegler catalysts. |
