A USEFUL METHOD FOR THE SYNTHESIS OF NEODYMOCENE HOMOGENEOUS CATALYSTS FOR ETHYLENE POLYMERIZATION

The direct alkylation of the neodymium complex Cp2*NdCl2Li(OEt2)2 (1) by butylethyl-magnesium gives rise to the production of efficient homogeneous catalytic species for ethylene polymerization. The polymers are highly linear, vinyl terminated, and present narrow molecular weight distributions (M(w)/M(n) = 2). The observed molecular weights are strongly dependent on the reaction temperature and ethylene pressure. This catalytic system is shown to be more active than classical Ti/Mg heterogeneous catalysts, and even more stable in a batch reactor at 160-degrees-C and 6 bar. Experiments conducted in a pilot plant (continuous flow autoclave reactor) have been performed at 200-degrees-C and 1200 bar. These gave rise to the conclusion that the catalyst in these conditions is still able to perform the homopolymerization of ethylene with a very high productivity, even in the presence of but-1-ene in the reaction mixture.