Disclosed are catalyst systems and methods of making the catalyst systems
for the polymerization of an olefin containing a solid titanium catalyst
component containing an inorganic titanium compound, a magnesium alcohol
adduct made from an inorganic magnesium compound and an alcohol, and a
porous support having at least one of a certain specific surface area, a
certain pore volume, and a certain median particle size. The catalyst
system may further contain an organoaluminum compound and optionally an
organosilicon compound. Also disclosed are methods of making polyolefins.