Homogeneous Vanadium-Based Catalysts for the Ziegler-Natta Polymerization of a-Olefins

Abstract

Although their activity is often inferior to that of other systems, the use of vanadium-based catalysts in homogeneous Ziegler Natta polymerizations allows the preparation of high-molecular-weight polymers with narrow molecular-weight distributions, ethene/-olefin copolymers with high -olefin incorporation, and syndiotactic polypropene. The main reason for the low activity of these catalysts is their deactivation during catalysis by reduction of active vanadium species to low-valent, less active or inactive species. We here present an up-to-date review of this area with particular emphasis on the attempts to improve catalyst performance and stability by the use of additives or ancillary ligands.