The selectivity of ethylene oligomerization into higher α-olefins using the system TiCl 4C 2H 5AlCl 2

Abstract

The effect of the Al/Ti ratio, and of the catalyst and monomer concentrations and of impurities (water, alcohols, AlCl 3, CO 2) that are active with respect to catalyst components has been investigated in relation to the polymer chain structure, the nature of functional groups, the number average molecular weight and the polydispersity coefficient of ethylene oligomerization products, using the system TiCl 4C 2H 5AlCl 2. It is shown that the synthesis of higher linear α-olefins by ethylene oligomerization on the system TiCl 4C 2H 5AlCl 2 in benzene or toluene media with a selectivity exceeding 95 wt. % for ethylene is possible in the temperature range 20–40°C, at pressures 25–30 atm, TiCl 4 concentration 0·5-1·5 g/l., Al/Ti molar ratio = 2–16. It is proposed that such a narrow range of variation in parameters of the process in the ethylene oligomerization into higher α-olefins on the system in question stems from the occurrence of side reactions at active centres of oligomerization, and is due to a difference in the types of active centres formed.