PROCESS FOR FORMING A ZIEGLER-NATTA CATALYST SYSTEM HAVING A CONTROLLED MORPHOLOGY

A pre-catalyst is formed by reacting butylethylmagnesium with an alcohol to form a magnesium alkoxide compound, followed by contacting the magnesium alkoxide compound with a phosphorous compound to form a magnesium alkoxide phosphorous compound mixture. The magnesium alkoxide phosphorous compound mixture is subsequently reacted with TiC1₄ to form a MgC1₂ support. The MgC1₂ support is then contacted with an internal donor while being heated to form a first catalyst slurry, which is then contacted with TiC1₄ while being heated to form a second catalyst slurry. The second catalyst slurry is next contacted with TiC1₄ while being heated to form a third catalyst slurry, which is washed and dried, resulting in a highly active pre-–catalyst with controlled morphology. The pre-catalyst may be combined with one or more co-catalysts and optionally one or more external electron donors to form an active catalyst system, which may be used for the polymerization of olefins.