CONTINUOUS SOLUTION POLYMERIZATION OF ETHYLENE USING METALLOCENE CATALYST SYSTEM, ZIRCONOCENE DICHLORIDE METHYLALUMINOXANE/TRIMETHYLALUMINUM/

A high-pressure, high-temperature continuous stirred-tank reactor (CST R) system having approximately an ideal residence time distribution (R TD) has been set up for the polymerization of olefins utilizing metall ocene catalysts. Preliminary experiments of ethylene polymerized with the metallocene catalyst system zirconocene dichloride (Cp2ZrCl2)/modi fied-methylaluminoxane (MMAO)/trimethylaluminum (TMA) in toluene at 15 00 psig have been carded out, The reactor system showed good control o ver temperature, pressure, and ethylene feed rate. The steady state wa s obtained after four mean residence times (4 tau's). With increasing Cp2ZrCl2 concentration, the molecular weight (MW) of polyethylene (PE) decreased and the catalyst activity (kg of PE/([ethylene].g of cataly st)) increased. With increasing temperature between 140 and 200 degree s C, the MW of PE decreased and molecular weight distribution (MWD) po lydispersity increased. PEs with weight-average molecular weight (M-w) 18 000-52 000 were obtained. The catalyst activity decreased with inc reasing temperature with an apparent, activation energy of -93 kJ/mol. The deactivation of the catalyst is first-order with the rate constan t k(d) = 2.1 x 10(-3) s(-1) at 140 degrees C. The rate constants of pr opagation and beta-scission at 140 degrees C are k(p) = 5 x 10(3) (M.s )(-1) and k(tr,beta) = 3 s(-1).