Compound catalyst system for synthesizing polyethylenes or copolymers of ethylene having bimodal or broad molecular weight distributions, process for preparing the same and use of the same

A compound catalyst system used for synthesizing polyethylenes or copolymers of ethylene having bimodal or broad molecular weight distributions, comprising:

• A) a solid catalyst component containing a metallocene compound and titanium or vanadium derived from a non-metallocene transition metal compound, obtained by reacting
• (1) a magnesium halide solution, wherein said magnesium halide solution is a homogeneous solution formed by dissolving magnesium halide in a solvent system consisting essentially of an organic epoxy compound and an organophosphorus compound, with the amounts of said epoxy compound and said organophosphorus compound being respectively 0.2-10 moles and 0.1-3 moles, per mole of magnesium halide,
• (2) one or more of C1-C20 organic alcohols,
• (3) a non-metallocene transition metal compound of titanium or vanadium;
• (4) a metallocene compound, and
• (5) an aluminoxane compound,
• wherein the amounts of components (2)-(5) are respectively 0.2-95 moles, 0.2-4.0 moles, 0.05-0.6 mole and 0.15-20 moles per mole of said magnesium halide;
• and
• B) an organoaluminum compound having the formula of AlRmX3−m wherein R is hydrogen or a hydrocarbyl group having from 1 to 20 carbon atoms, X is halogen, the value of m is larger than 0 and equal to or smaller than 3, and/or the aluminoxane compound used in the solid catalyst component A) wherein the ratio of the solid catalyst component A) to the component B), in terms of the molar ratio of the total transition metals contained in the non-metallocene transition metal compound and the metallocene compound to aluminum contained in the component B), is from 0.0001:1 to 0.05:1.