A diphenoxybis(β diketonato)titanium complex, (dbm) 2Ti(OPh) 2, was synthesized and the corresponding MgCl 2\|supported catalyst was prepared by impregnation method. The polymerization activity was drastically improved by using MgCl 2\|supported (dbm) 2Ti(OPh) 2 activated by aluminoxane (MAO) for ethylene polymerization (1.5×10 5 g/molTi with the heterogeneous catalyst and 1.3×10\+3 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 5.1×10 5 to 2.8×10\+5 by 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 5.0×10 5 or so. It is revealed that the MgCl 2\|supported β diketonato titanium complex is influenced by the polymerization conditions markedly.
