Olefin polymerization and copolymerization catalyst

A solid, hydrocarbon-insoluble catalyst or catalyst component for the polymerization of propylene or copolymerization of propylene with up to 20 mole percent of ethylene or a higher alpha-olefin, comprising a product formed by:

• A. forming a solution of a magnesium-containing species in a liquid, wherein the magnesium-containing species is formed by reacting a magnesium-containing compound with carbon dioxide or sulfur dioxide;
• B. precipitating solid particles from the solution of the magnesium-containing species by treatment with a titanium compound or complex;
• and
• D. treating the precipitated particles with a titanium compound and an electron donor;
• wherein the treated precipitated particles from Step D comprise a magnesium component and at least one of a hafnium component or a zirconium component, and wherein at least one of hafnium or zirconium is introduced into at least one of (i) the aforesaid magnesium-containing species in Step A by reacting the magnesium-containing compound or species with carbon dioxide or sulfur dioxide and at least one of a hafnium-containing or zirconium-containing compound or complex, or (ii) the aforesaid solid particles precipitated in Step B by treatment of the magnesium-containing species with a titanium compound or complex and at least one of a hafnium or zirconium compound or complex;
• or (iii) the aforesaid precipitated particles treated in Step D by treatment of the precipitated particles with a titanium compound, an electron donor and at least one of a hafnium or zirconium compound or complex.