A diphenoxybis(βdiketonato)titanium complex

(dbm)2Ti(OPh)2

was synthesized and the corresponding MgCl2-supported catalyst was prepared by impregnation method. The polymerization activity was drastically improved by using MgCl2-supported (dbm)2Ti(OPh)2 activated by aluminoxane (MAO) for ethylene polymerization (1.5×105g/molTi with the heterogeneous catalyst and 1.3×103 g/molTi with the homogeneous one). When the molar ratio of Al to Ti increased from 50 to 1000

the crystallinity and molecular weight of polyethylene were decreased rapidly.Also

The molecular weight of polyethylene was decreased from 5.1×105to 2.8×105by increasing the molar content of titanium of the supported catalyst from 0.5×10-5 to 3.42×10-5.After 60 min of the reaction

the molecular weight was at 5.0×105or so. It is revealed that the MgCl2-supported β-diketonato titanium complex is influenced by the polymerization conditions markedly.