Through immobilization of two iron-based complexes, [((2,6-MePh)N = C(Me))(2)C5H3,N]FeCl2 (1) and [((2,6-iPrPh)N = C(Me))(2)C5H3N]FeCl2 (2), on SiO2 pretreated with tetraethylaluminoxane (TEAO), two supported iron-based catalysts, 1/TEAO/SiO2 (3) and 2/TEAO/SiO2 (4), were prepared. These two supported catalysts 3 and 4 could be used to catalyze ethylene polymerization with moderate polymerization activity and prepare linear high-density polyethylene with bimodal molecular weight distribution (MWD). It was demonstrated that immobilization of catalyst could significantly improve molecular weight (MW) of high-MW fraction of the resultant polyethylene, as well as maintain bimodal MWD of polyethylene produced by the corresponding homogeneous catalysts. Such bimodal MWD of polyethylene produced by supported iron-based catalysts could be well tailored by varying polymerization conditions, such as ethylene pressure and molar ratio of Al to Fe. It has been proven that TEAO is an efficient activator for both homogeneous and heterogeneous iron-based catalysts for producing polyethylene with bimodal MWD. (C) 2004 Wiley Periodicals, Inc.