Ethylene polymerization with highly active catalysts prepared using Grignard reagent has been systematically studied. With the catalyst from the reaction of TiCl4with Grignard compound in dilute solution

ethylene polymerization exhibited high activities and decay kinetics

and very fine PE particles with irregular shape were produced

whereas with the catalyst prepared in concentrated solution

relatively low activities and steady kinetics were observed and larger PE particles were obtained. When the Grignard reagent reacted first with SiCl4 to produce the MgCl2 granules and then TiCl4was supported

the catalyst gave the highest activity and PE particles with better morphology were obtained.