Process for the production of a catalyst component for use in the polymerization of .alpha.-olefins

A process for the production of a catalyst component for use in polymerization of alpha-olefins which comprises:

• reducing titanium tetrachloride with an organoaluminum compound having the general formula AlR.sub.n x.sub.3-n wherein R represents a hydrocarbon group having 1 to 18 carbon atoms, X represents a halogen, and n represents a number expressed as 0 <
• n .ltoreq. 3 to obtain a brown or black-brown titanium trichloride reduced solid containing aluminum compounds;
• removing aluminum compounds from said brown or black-brown titanium trichloride reduced solid;
• and thereafter
• contacting said brown or black-brown titanium trichloride reduced solid in an inert diluent with an activator selected from the group consisting of a complex of diisoamyl ether and titanium tetrachloride, and a mixture of diisoamyl ether and titanium tetrachloride at a temperature within the range of from -30.degree. to 100.degree. C for at least 30 minutes, wherein the mole ratio of diisoamyl ether to titanium trichloride is at least 0.1 and the concentration of titanium tetrachloride in the liquid phase is maintained at at least 1 volume percent.