Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization

Abstract

Oxovanadium(IV) complexes with [ONNO]-type tetradentate Schiff base ligands: salen, acacen, aceten, acetph (H2salen = N,N'- ethylenebis(salicylideneimine), H2aceten = N,N'-ethylenebis(2- hydroxyacetophenoneimine), H2acacen = N,N'- ethylenebis(acetylacetonimine), H2acetph = N,N ' - phenylene - 1,2-bis (2-hydroxyacetophenoneimine)), were the first time investigated in ethylene polymerization and ethylene/1-octene copolymerization processes. In general, all these complexes are moderately active precatalyst for ethylene polymerization upon activation with EtAlCl2 and they give high molecular weight linear polyethylenes. Their activity in copolymerization was found relatively low. However, they yielded copolymers with high 1-octene incorporation even at low comonomer concentrations in the feed. The catalytic performance in homo- and copolymerization was influenced by both the ligand structure and polymerization parameters (Al/ V molar ratio, polymerization temperature, comonomer feed concentration). In addition, the [VO(acacen)] was supported onto magnesium supports, and in the presence of various cocatalyst and at different reaction conditions it was screened as the catalyst of choice for ethylene homo- and copolymerization. © Springer Science+Business Media New York (outside the USA) 2014.