Effect of the zeolite support on the polymerization of propylene with immobilized ansa-zirconocene catalysts

Anchored aluminoxanes are synthesized by the reaction of aluminum alkyls AlMe 3 and Al( i -Bu) 3 with water contained in the intracrystalline cavities of synthetic and natural zeolites (NaY (Si: Al = 5), HZSM-5 (Si: Al = 17 or 34), NH 4 ZSM-5 (Si: Al = 32), NaZSM-5 (Si: Al = 42), and clinoptilolite-containing tuff) and are used for the synthesis of heterogenized complexes of ansa -zirconocenes ( rac -C 2 H 4 (Ind) 2 ZrCl 2 , rac -Me 2 Si(Ind) 2 ZrCl 2 , and rac -[1-(9-η 5 -Flu)-2-(5,6-cyclopenta-2-Me-1-η 5 -Ind)C 2 H 4 ]ZrCl 2 ) active in the polymerization of propylene. The nature of the zeolite support determines the content of zeolite water and affects the formation of anchored alkylaluminoxanes and the activity of immobilized catalysts. Among the studied catalytic systems supported on zeolites, NaY and NaZSM-5 are the most efficient for the polymerization of propylene. PP synthesized with the supported zirconocene catalysts has a higher molecular mass and a wider molecular-mass distribution than those in the case of the corresponding homogeneous catalyst. The index of isotacticity and the content of pentads mmmm in PP prepared with immobilized metallocenes with the C 2 symmetry, such as rac -C 2 H 4 (Ind) 2 ZrCl 2 and rac -Me 2 Si(Ind) 2 ZrCl 2 , are likewise higher. The stereoselectivity of supported catalysts depends on the zeolite nature.