Ethylene polymerization and ethylene/1-hexene copolymerization using homogeneous and heterogeneous unbridged bisindenyl zirconocene catalysts

Abstract

Unbridged bis-substituted-indenyl zirconocene complexes, [(2,4-Me 2Ind) 2ZrCl 2, Met-1; (2,4,6-Me 3Ind) 2ZrCl 2, Met-2], were supported on silica and montmorillonite carriers (resulting in silica-supported catalysts MS-1 and MS-2, and montmorillonite-supported catalyst MT-1). Ethylene polymerization by homogeneous and heterogeneous catalysts showed high activity, affording polyethylenes with high molecular weight. The catalytic activity and the molecular weight of the polymer were improved using the heterogeneous systems. The activities for the ethylene/1-hexene copolymerization by heterogeneous systems were lower than those using homogeneous systems, however, the comonomer was incorporated efficiently into polymer in both the homo- and the heterogeneous systems, and moreover, the microstructure of the copolymer derived from the heterogeneous catalysts showed different characteristics from those resulting from the homogeneous systems. The r E r H values of the heterogeneous catalysts (1.82 for MS-1 and 0.70 for MS-2), are quite different from those of their homogeneous analogues (1.25 for Met-1 and 1.26 for Met-2).