Ethylene slurry polymerization using nickel diimine catalysts covalently-attached onto MgCl_2-based supports

摘要

MgCl_2/alcohol adducts were recrystallized with alkyl aluminums and used as catalysts supports for nickel diimine complexes functionalized with amine groups. These supported catalysts were used to polymerize ethylene in a slurry reactor. The MgCl_2-based supported nickel diimine catalysts had higher activities than the equivalent SiO_2-supported nickel diimine catalysts, even without the use of activators. These catalysts made polyethylene with melting temperatures and molecular weights higher than those made with the equivalent homogeneous catalysts. Interestingly, the catalyst activity and polymer molecular weight could be controlled by changing the support composition. In addition, covalent chemical bonds between the functionalized nickel diimine complex and the MgCl_2-based supports avoided catalyst leaching during polymerization, leading to the production of polymer particles with good morphology. The mechanical strength of the resulting polymer particles, however, was lower than those made with SiO_2-supported nickel diimine catalysts.