The MgCl2/SiO2 complex support was prepared by spray drying using alcoholic suspension which contained MgCl2 and SiO2. The complex support reacted with TiCl4 and di-n-butyl phthalate, give the catalyst for propylene polymerization. The catalyst was spherical and porous with high specific surface area. The multistage polymerization of propylene for high impact propylene was studied with the catalyst system. It was found that the final high impact polypropylene after two stages of reaction was still freeflowing, spherical granules. Homopolypropylene with pore diameter between 100 nm and 10000 nm was suitable for EPR to fill in during ethylene-propylene copolymerization. The high impact polypropylene showed good balance between stiffness and toughness.
