Polyolefin is the most important product of petrochemical industry

and majorly related to polyethylene

meanwhile α-olefins are not only co-monomer in co-polymerization but also basic substance for fine-chemical industry. Therefore the national ethylene industry represents the technical development of petrochemical industry. Regarding the newly developing process in ethylene industry

late-transition metal precatalysts achieve highly activities in oligomerization and polymerization

in which the resultant polyethylenes potentially become new plastic materials of polyethylenes. It is still a hot topic of developing new precatalysts through modifying coordination ligands to enhance the activities and thermal-stabilities of late-transtion metal complexes ; the finely controlled microstructures of resultant polyethylenes resulted the better properties and provided essentials toward industrial process. Relied on variations of ligands' classifications

the complex precatalysts of iron

cobalt and nickel have been compared in their performances in ethylene oligomerization and polymerization. The new progress has been reviewed

specially focusing on our researches.