Advances in supported metallocene catalysis
Polimery 2000, No 5, 314
SummaryA kinetic, active centre, and morphological analysis has been carried out on the polymerization of ethylene and propylene in hydrocarbon, aromatic and chloroaromatic media using selected homogeneous and silica supported metallocene catalysts activated by methylaluminoxane (MAO). A number of procedures for supporting selected model zirconocene compounds (biscyclopentadienylzirconium dichloride and ethylenebisindenylzirconium dichloride) on different types of silica have been investigated. It is established that the overall activities and kinetic behaviour of these supported catalysts are strongly affected by the procedure used for the catalyst preparation. In general supported metallocene catalysts were shown to have lower activities and also lower numbers of propagating active centers than did the corresponding soluble catalyst systems. MAO pretreated silica catalysts were shown by SEM studies to produce polymer with good morphology and the results obtained indicated that silica fragmentation producing microreactor behaviour could be obtained in these polymerizing catalyst systems.