Method of making a ziegler-natta catalyst

A method of making a Ziegler-Natta catalyst comprising the steps of

• a) providing a silica seeding agent including silica particles having an average particle diameter of 0.001 up to less than 1.0 micron, a porosity of less than about 0.5 cc/g as measured by nitrogen absorption and a radius which does not vary by more than about 20% from the center of the particles to any point on the particle surface;
• b) contacting the silica seeding agent with a surface modifying agent having a formula selected from the group consisting of RMgX, MgR′R″ and R′MgOR″, wherein R, R′ and R″ are each individually a moiety selected from an alkyl, cycloalkyl, aryl or alkaryl group, and X is a halogen selected from the group consisting of chlorine, bromine and iodine, to provide a pretreated silica seeding agent;
• c) providing a non-aqueous liquid magnesium halide/alkanol complex;
• d) combining the non-aqueous liquid magnesium halide/alkanol complex with the pretreated silica;
• e) crystallizing the magnesium halide onto the silica particles to form approximately spherical catalyst support particles;
• f) recovering the catalyst support particles;
• g) treating the catalyst support particles with a transition metal compound to form a solid catalyst component;
• h) recovering the solid catalyst component;
• and
• i) combining the solid catalyst component with an organo-aluminum cocatalyst.

A method for the polymerization of an olefin comprising:

• a) providing a Ziegler-Natta catalyst in accordance with a method including the steps of
• i. providing a silica seeding agent including silica particles having an average particle diameter of 0.001 up to less than 1.0 micron, a porosity of less than about 0.5 cc/g as measured by nitrogen absorption, and a radius which does not vary by more than about 20% from the center of the particles to any point on the particle surface,
• ii. contacting the silica seeding agent with a surface modifying agent having a formula selected from the group consisting of RMgX, MgR′R″ and R′MgOR″, wherein R, R′ and R″ are each individually a moiety selected from an alkyl, cycloalkyl, aryl or alkaryl group, and X is a halogen selected from the group consisting of chlorine, bromine and iodine, to provide a pretreated silica seeding agent,
• iii. providing a non-aqueous liquid magnesium halide/alkanol complex,
• iv. combining the non-aqueous liquid magnesium halide/alkanol complex with the pretreated silica,
• v. crystallizing the magnesium halide onto the silica particles to form approximately spherical catalyst support particles,
• vi. recovering the catalyst support particles,
• vii. treating the catalyst support particles with a transition metal compound to form a solid catalyst component,
• viii. recovering the solid catalyst component, and
• ix. combining the solid catalyst component with an organo-aluminum cocatalyst to provide the Ziegler-Natta catalyst;
• and,
• b) contacting the olefin with the Ziegler-Natta catalyst under olefin polymerization reaction conditions.