High activity solid catalyst for producing low-, medium-, and high-density polyethylenes by slurry phase polymerization, process for preparing the same and use of the same in ethylene polymerization

A high activity solid catalyst for producing low-, medium- high-density polyethylenes by a slurry phase process, comprising:

• (A) a main catalyst component containing titanium, obtained by reacting powdered magnesium with an alkyl halide in a hydrocarbon solvent, optionally in the presence of a first electron donor compound ED1, to form a magnesium halide in the nascent state, followed by successively treating and magnesium halide with an alcohol compound in an alcohol to Mg molar ratio of 0.2-6:1 and an alkyl aluminum compound, then reacting the resulting suspension of the spheroidal, porous solid complex carrier with a titanium compound in the presence of a second electron donor compound ED2 an alkyl aluminum compound, wherein said first and second electron donor compounds are organic compounds containing at least one atom of oxygen, sulfur, nitrogen, silicon or phosphorus;
• and
• (B) an organometallic compound as cocatalyst;
• wherein the ratio of the cocatalyst to the main catalyst component, in terms of the molar ratio of the metal contained in component (B) to titanium contained in component (A), is 20-400:1.