Ultra-high molecular weight, ultra-fine particle size polyethylene, preparation method therefor and use thereof

A method for preparing an ultra-high molecular weight, ultra-fine particle size polyethylene powder, comprising:

• carrying out ethylene polymerization in presence of a catalyst at a polymerization temperature of −20° C. to 100° C., wherein, in the ethylene, a content of carbon monoxide is not higher than 5 ppm, a content of carbon dioxide is not higher than 15 ppm, and a content of conjugated diene is not higher than 10 ppm,
• wherein the catalyst is prepared by a method comprising steps of:
• (a) mixing magnesium halide, an alcohol compound, a titanate compound, a first portion of an internal electron donor compound, and a solvent to prepare a mixture I;
• (b) adding the mixture I into a reactor, preheating to −30° C.-30° C., and adding a first portion of a titanium compound to form a reaction mixture;
• or adding the first portion of the titanium compound into the reactor, preheating to −30° C.-30° C., and adding the mixture I to form the reaction mixture;
• (c) raising the temperature of the reaction mixture and maintaining the temperature at 90° C.-130° C. for 0.5-3 hours, adding a second portion of the internal electron donor compound to the reaction mixture, and continuously reacting;
• (d) filtering the reaction mixture to remove liquid, adding a second portion of the titanium compound, and continuously reacting;
• and
• (e) obtaining the catalyst after post-treatment.