Ethylene Oligomerization Catalyzed By Bis(indenyl) Zirconium Complexes

Linear low x-olefins are important comonomers to produce LLDPE and HDPE and many fine chemicals, such as biodegradable detergents, lubricants. A series of zirconocenes Ind2ZrCl2(A), CpZrCI2(B), Cp2Zr(0C6H4-p-CH3)2(C), Ind2Zr(0C6H4-p-CH3)2(D), Ind2Zr(0C6H4-3 -5 -Mej2(E), Ind2Zr(0C6H4)2(F), lnd2ZrCl(0C6H4-p- CH3)(G) were synthesized according to the literature. The binary Ziegler-Natta catalytic systems consisting of A, B, C, D, E, F, G and organic aluminum compounds in ethylene oligomerization were investigated from aging temperature, aging time and reaction temperature. 1) The catalytic properties of D with different cocatlysts: Et3A1(I), Et2A1C1(II), Et3A12CI3(III), EtA1C12(IV), EAO(V) were studied. D/ll system catalyzed ethylene oligomerization and had the highest activity. Polyethylene were produced in D/J and D/V systems. 2) The systems of A, B, C, D and II were compared under the optimal reaction conditions: the activity of A526g1g(Zr).h, W=150g/g(Zr).h, C=235g1g(Zr).h, D1666g/g(Zr).h. lit can be concluded that Bis(indenyl)Zirconium complexes are generally more active than Bis(Cyclopentadienyl)Zirconium complexes. 3) The electronic effects of ligands in the systems of A, G, E/II were investigated. The order of their catalytic activity was: E>G>A. The replacement of chlorine by the aryloxy group led to the improvement of catalytic activity. 4) The effects of varying aryl substitutes on the catalytic behavior iv of Ind2Zr(OPhR),/Et2AlCl (R=H, p-Me, 3-5-Me2) for the ethyleneoligomerization were carried out. The electronic effects (HammettFunction) could explain the experimental data.