Dual‐functional catalysis for ethylene polymerization to branched polyethylene. II. Kinetics of ethylene polymerization with a mixed homogeneous–heterogeneous Ziegler–Natta catalyst system

The previous paper in this series described several catalytic systems which can be used for simultaneous ethylene dimerization to 1‐butene and copolymerization of the in situ ‐formed olefin with ethylene to form branched polyethylene. Such catalytic systems allow the synthesis of linear low‐density polyethylene from a single monomer source. This article presents a more detailed description of one of the dual‐functional catalyst systems studied, a mixed homogeneous–heterogeneous Ziegler–Natta catalyst, Al(C 2 H 2 ) 3 –Ti(Oi‐C 3 H 7 ) 4 –TiCl 4 /MgCl 2 /polyethylene, at 90°C. Discussed are kinetics of ethylene dimerization with the soluble component, Al(C 2 H 5 ) 3 –Ti(Oi–C 3 H 7 ) 4 , and the effects of aluminum alkoxides on the system. Addition of the ethylene dimerization catalyst to the solid component, Al(C 2 H 5 ) 3 –TiCl 4 /MgCl 2 /polyethylene, results in a partial decrease in polymerization activity. Some of the decrease can be attributed to the presence of 1‐butene in the reaction medium. Measurement of the reactivity ratio k EE / k EB for two catalytic systems, the solid component and the title dual‐functional catalyst, demonstrated that the presence of the dimerization component results in a twofold increase in the reactivity ratio, from 20 to ca. 40.