Olefin polymerization procatalyst compositions and method of preparation

A method of making a solid procatalyst composition for use in a Ziegler-Natta olefin polymerization catalyst composition, said method comprising:

• (a) contacting a solid precursor composition comprising a magnesium compound with a halogenating agent and an internal electron donor in any order, in a suitable reaction medium under metathesis reaction conditions, and separating the solid reaction product;
• (b) optionally contacting the solid reaction product from step (a) with a halogenating agent in a suitable reaction medium one or more times under metathesis reaction conditions and separating the solid reaction product;
• (c) contacting the solid reaction product of step (a) or optional step (b) with a halogenating agent and a liquid diluent comprising an aliphatic ether, aliphatic polyether or aliphatic (poly)glycol ether one or more times under metathesis reaction conditions in a suitable reaction medium;
• (d) separating the solid procatalyst from the reaction medium of step (c);
• (e) extracting the solid procatalyst composition by contacting the same one or more times with a liquid diluent at an elevated temperature for a period of time sufficient to prepare a solid procatalyst composition having a decreased titanium content compared to the titanium content of the solid procatalyst composition before said extraction, and
• (f) recovering the solid procatalyst composition.