Catalyst compositions comprising small silica support materials and methods of use in polymerization reactions

摘要

Methods are provided to prepare a catalyst system that includes at least one titanium compound, at least one magnesium compound, at least one electron donor compound, at least one activator compound, and at least one silica support material, the at least one silica support material having a median particle size in the range of from 20 to 50 microns with no more than 10% of the particles having a size less than 10 microns and no more than 10% of the particles having a size greater than 50 microns and average pore diameter of at least ≧220 angstroms.