Method of Producing Polyethylene

A method of producing a polyethylene polymer, the method comprising:

• S1) introducing a transition metal into a support to generate a composition comprising a transition metal-supported catalyst and unsupported transition metal, wherein the transition metal-supported catalyst has an initial catalytic activity;
• S2) washing the transition metal-supported catalyst with an organic solvent a total of two to ten times in a first stage at a first temperature T1 and in a second stage at a second temperature T2 to generate a washed transition metal-supported catalyst,
• S3) introducing the washed transition metal-supported catalyst into a reactor and then injecting ethylene gas into the reactor under conditions effective to produce a polyethylene polymer;
• and
• S4) washing the produced polyethylene polymer,
• wherein T1 is 60 to 80° C. and T2 is 10 to 50° C.